copi 


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Preliminary  Report 


ON 


Organization  and  Method 


OF 


v» 


Investigations 


ILLSNOIS  STATE 
GEOLOGICAL  SURVfc 
U  R  B  A  N  A  1I5RARY 

University  of  Illinois 

19   13 


c 


ILLINOIS 
COAL   MINING   INVESTIGATIONS 

CO-OPERATIVE  AGREEMENT 


State  Geological  Survey 

Department  of  Mining  Engineering,  University  of  Illinois 

U.  S.  Bureau  of  Mines 


The  Forty-seventh  General  Assembly  of  the  State  of  Illinois,  with  a 
view  of  conserving  the  lives  of  the  mine  workers  and  the  mineral 
resources  of  the  State,  authorized  an  investigation  of  the  coal  resources 
and  mining  practices  of  Illinois  by  the  Department  of  Mining  Engineer- 
ing of  the  University  of  Illinois  and  the  State  Geological  Survey  in  co- 
operation with  the  United  States  Bureau  of  Mines.  A  cooperative  agree- 
ment was  approved  by  the  Secretary  of  the  Interior  and  by  representa- 
tives of  the  State  of  Illinois. 

The  direction  of  this  investigation  is  vested  in  the  director  of  the 
United  States  Bureau  of  Mines,  the  director  of  the  State  Geological 
Survey,  and  the  head  of  the  Department  of  Mining  Engineering,  Uni- 
versity of  Illinois. 

The  reports  of  the  investigation  are  printed  in  the  form  of  bulletins. 
For  copies  of  these  bulletins  or  any  information  regarding  the  work, 
address  "Coal  Mining  Investigations,  University  of  Illinois,  Urbana, 
Illinois." 


ILLINOIS  STATE  GEOLOGIC Al_  SI    -VE-jT 

3  3051  00006  3812 


ILLINOIS 
COAL    MINING   INVESTIGATIONS 

CO-OPERATIVE    AGREEMENT 


State  Geological  Survey 

Department  of  Mining  Engineering,  University  of  Illinois 

U.  S.  Bureau  of  Mines 


PRELIMINARY     REPORT 

ON 

ORGANIZATION     AND     METHOD 

OF 

INVESTIGATIONS 


ILLINOIS  STATE 

GEOLOGICAL  SURVEY 

LIBRARY 


Springfield,  III. 
Illinois  State  Journal  Co.,  State  Printers 


CONTENTS. 


Page  . 

Introduction 5 

Personnel  of  the  investigation 8 

Method  of  conducting  the  investigation 10 

Study  of  geological  features 25 

1.  Coal  resources  of  Illinois 25 

2.  Scope  of  new  work  on  geology  of  the  coal  fields 26 

3.  Chemical  quality  of  Illinois  coals 26 

4.  Utilization  of  clay  materials  of  coal  mines 28 

5.  Safeguards  of  gas  wells  and  oil  wells  in  the  coal  fields 2S 

Study  of  the  mining  methods 30 

1.  Systems  of  mining 30 

2.  Blasting  and  explosives 31 

3.  Timbering 31 

4.  Haulage 33 

5.  Hoisting 33 

6.  Ventilation  and  mine  gases 35 

7.  Mine  stoppings 35 

8.  Humidity  of  mine  air 36 

9.  Coal  dust 43 

10.  Machine  cuttings 46 

11.  Preparation  of  coal  for  market 47 

Appendix  "A" 48 

Geology  of  the  Illinois  coal  fields 48 

Introduction 4S 

The  coal-bearing  area 4S 

The  coal-bearing  formations 48 

Pottsville 49 

Carbondale 49 

McLeansboro 50 

The  spoon-shaped  structural  basin 50 

Mining  centers  and  districts 51 

Chemical  character  of  Illinois  coals 56 

Appendix  "B" 59 

Illinois  mining  systems 59 

Room-and-pillar 59 

Unmodified 59 

Panel  system 61 

Longwall 63 

Stripping 64 

Appendix  "C" 67 

Equipment  of  coal  dust  laboratory  at  Urbana,  Illinois 67 

Description  of  apparatus 67 

Operation  of  apparatus 70 


ILLUSTRATIONS. 


Ftgs.  Page  . 

1.  Diagram  showing  coal  production  at  intervals  of  ten  years 6 

2.  Map  showing  mines  selected  for  cooperative  investigation 11 

3.  Coal  grinder  for  mine  sampling 27 

4.  Riffle  for  reducing  mine  samples 27 

5.  Sketch  showing  arrangement  of  shots  in  coal  face 31 

6.  Sketch  of  typical  room  showing  location  of  timber ; 32 

7.  Tonnage  and  percentage  of  coal  hauled  by  different  methods 33 

8.  Mine-air  sample  report  card 34 

9.  Approximate  coal  areas  (Bement)  showing  U.  S.  Weather  Bureau  hygrograph  stations  and 

mines  at  which  hygrometers  have  been  installed 38 

10.  Hygrometer  and  hygrometer  shelter 40 

11.  ) 

12.  }  Diagrams  showing  moisture  in  air-current  in  summer,  winter,  and  spring 42 

13.  j 

14.  Curves  showing  relative  explosibility  of  coal-dusts 45 

15.  Map  showing  coal-measures  area  in  Illinois 48 

16.  Map  showing  production  of  coal,  calendar  year  of  1911 50 

17.  Plan  of  room-and-pillar  mine 60 

18.  Plan  of  panel  mine 62 

19.  Plan  of  longwall  mine 64 

20.  Stripping-mine  thorough-cut 65 

21.  Stripping-mine  haulage  way 65 

22.  Stripping-mine  coal  face 66 

23.  Stripping-mine  second  cut 66 

24.  Coal-dust  laboratory,  University  of  Illinois 67 

25.  Explosibility  apparatus  in  dust  laboratory 68 

26.  Detail  of  dust  explosibility  apparatus 69 


ORGANIZATION    AND    METHOD     OF     INVESTI- 
GATIONS. 


INTRODUCTION. 


Illinois  lias  long  been  an  important  contributor  to  the  coal  production 
of  the  country.  The  first  record  of  coal  in  the  United  States  is  con- 
tained in  the  journal  of  the  Jesuit  Missionary,  Father  Hennepin,  who 
as  early  as  1679  reported  a  "cole"  mine  on  the  Illinois  River  near  the 
present  city  of  Ottawa. 

The  recorded  output  to  the  close  of  1911  approximates  850  million 
tons,  a  record  surpassed  in  this  country  only  by  Pennsylvania. 

The  increase  in  production,  practically  doubling  each  ten-year  period 
(fig.  1),  is  but  parallel  to  that  generally  experienced  elsewhere.  It 
emphasizes  the  need  for  the  fullest  possible  knowledge  of  the  coal  re- 
sources themselves,  and  also  of  the  practices  that  will  make  coal  mining 
as  safe  and  as  profitable  as  possible  for  all  affected  by  the  industry. 

Mining  is  co-important  with  agriculture,  both  being  indispensable  to 
modern  life  and  commercial  development.  In  the  calendar  year,  1911, 
the  coal  mines  in  Illinois  produced  53,679,118  tons,  and  employed 
77,000  workmen.  Under  the  practice  which  has  developed  naturally, 
in  response  to  competitive  conditions,  possibly  50  per  cent  of  the  coal 
in  the  ground  has  been  lost,  and  a  large  part  of  the  mined  portion 
wasted  by  its  improper  or  inefficient  use.  Moreover,  2  to  3  lives  have 
been  lost  annually  for  every  1,000  miners  employed,  or  3  to  4  for  each 
million  tons  produced,  and  the  number  of  serious  injuries  has  been 
even  greater.  This  condition  is  due  to  the  rapid  expansion  of  the  coal 
mining  industry,  and  the  condition  under  which  such  mining  is  carried 
on  in  the  United  States.  Mining  is,  however,  but  one  of  the  industries 
in  which  such  records  have  been  made. 

It  is  believed  that  more  efficient  mining  methods  will  save  a  large  por- 
tion of  the  coal  resources  of  the  State,  cut  down  the  present  rate  of 
deaths  and  accidents,  and  make  for  safer  mining  investments. 

With  these  matters  in  mind,  the  Forty-seventh  General  Assembly  of 
Illinois  and  the  Secretary  of  the  Department  of  the  Interior  authorized 
an  investigation  of  coal  mining  under  a  cooperative  agreement  between 
the  State  Geological  Survey,  the  Mining  Department  of  the  University 


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INTRODUCTION.  7 

of  Illinois,  and  the  United  States  Bureau  of  Mines.  The  work  began 
in  the  summer  of  1911,  each  cooperating  party  furnishing  trained 
specialists  for  particular  phases  of  the  investigation. 

Before  the  work  was  planned  and  in  order  to  obtain  the  view-point 
of  those  connected  with  the  coal  mining  interests  in  Illinois,  a  number 
of  conferences  were  held  with  the  State  Mining  Board,  the  State  mine 
inspectors,  the  several  organizations  of  coal  operators,  and  with  the 
officials  of  the  United  Mine  Workers.  Many  suggestions  were  received 
from  each  of  these  organizations  that  were  of  great  assistance  in  select- 
ing typical  mines,  and  in  planning  and  carrying  out  the  work. 

The  United  States  Weather  Bureau,  has  heartily  cooperated  with  the 
Mining  Investigation  as  is  described  later  in  this  bulletin.  The  co- 
operation has  made  it  possible  to  gather  very  complete  information  upon 
the  atmospheric  conditions  in  Illinois  as  they  affect  the  ventilation  of 
mines  and  coal-dust  dangers. 

The  object  of  this  first  report  is  to  outline  the  organization,  scope  and 
methods  of  work,  and  to  suggest  the  nature  of  results  to  be  expected. 

Separate  reports  will  present  the  results  obtained  in  each  district  by 
the  geologists,  engineers,  and  chemists.  This  series,  together  with  reports 
on  special  subjects  and  summaries  for  the  whole  State,  will  define  the 
extent  and  character  of  Illinois  coal  beds ;  furnish  a  comprehensive 
description  of  methods  of  mining;  and  supply  much  new  information 
on  important  mining  problems. 


COAL   MINING   INVESTIGATIONS. 


PERSONNEL  OF  THE  INVESTIGATION. 


U.  S.  BUREAU    OF    MINES 

J.  A.  Holmes,  Director,  Washington,  D.  C. 

R.  Y.  Williams,  Mining  Engineer,  Urbana,  111. 

J.  J.  Rutledge,  Mining  Engineer,  Urbana,  111. 

A.  C.  Fieldner,  Chemist,  Pittsburgh,  Pa. 

N.  H.  Darton,  Geologist,  Urbana,  111. 

L.  A.  Scholl,  jr.,  Junior  Chemist,  Urbana,  111. 

J.  M.  Webb,  Foreman  Miner,  Urbana,  111. 

In  Consultation — 

George  S.  Rice,  Chief  Mining  Engineer,  Pittsburgh,  Pa. 
J.  K.  Clement,  Physicist,  Pittsburgh,  Pa. 

ILLINOIS    STATE    GEOLOGICAL    SURVEY 

F.  W.  DeWolf,  Director 
F.  H.  Kay,  Assistant  State  Geologist 
K.  D.  White,  Assistant  Geologist 
Prof.  S.  W.  Parr,  Consulting  Chemist 
J.  M.  Lindgren,  Chemist 

Analysts — 

F.  H.  Whittum 
S.  C.  Taylor 

J.  F.  Kohout 

G.  Simpson 
C.  W.  Sievert 
L.  T.  Fairhall 

DEPARTMENT    OF    MINING    ENGINEERING,    UNIVERSITY 
OF    ILLINOIS 

Prof.  H.  H.  Stoek,  Head  of  Department  of  Mining  Engineering 

S.  0.  Andros,  Mining  Engineer 

C.  M.  Young,  Mining  Engineer 

H.  H.  Lauer,  Mining  Engineer 

C.  W.  Porter,  Laboratory  Assistant 


PERSONNEL 


Samplers — 

C.  W.   Smith 
M.  L.  Nebel 
S.  T.  Wallage 
H.  L.  Stafford 
J.  E.  McDonald 


10 


COAL   MINING   INVESTIGATIONS. 


METHOD  OF  CONDUCTING  THE   INVESTIGATION. 


The  work  of  the  cooperative  investigation  is  intended  to  be  constructive 
as  well  as  statistical.  It  is  necessary  that  it  be  prefaced  and  based  npon 
accurate  information  and  that  all  existing  conditions  be  carefully  con- 
sidered if  the  results  are  to  be  of  benefit  to  the  coal  industry  of  Illinois. 
Deductions  from  these  investigations  should  aid  the  operators  and  miners 
of  the  State  to  produce  coal  more  safely,  more  cheaply,  and  less 
wastefully. 

In  Illinois,  according  to  the  report  of  the  State  Mining  Board  for 
the  year  ending  June  30,  1911,  there  are  845  mines.  Of  this  number, 
387  are  shipping  mines  and  458  are  non-shipping  mines,  commonly 
known  as  country  banks. 

The  size  of  the  mines  is  approximately  shown  by  Table  1. 


Table  1. — Tonnage  of  mines  for  1911 


Under  1,000. 

1,000 

and  under 

10,000. 

10, 000 

and  under 

50,000. 

50, 000 

and  under 

100,000. 

100,000 

and  under 

200,000. 

200,000 
and 
over. 

Total  mines. 

235 

213 

138 

82 

101 

76 

845 

For  the  purposes  of  this  investigation  the  State  has  been  divided  into 
nine  districts  as  shown  in  Table  2,  and  mines  working  the  same  bed 
under  similar  conditions  have  been  grouped  together. 

A  few  scattered  mines  which  have  not  been  included  in  any  of  these 
groups  are  so  similar  to  the  mines  in  nearby  districts  as  not  to  require 
special  examination. 

One  hundred  typical  mines  as  shown  in  fig.  2  have  been  chosen  for 
examination;  i.  e.,  about  one-quarter  of  the  shipping  mines.  Any  gen- 
eralization based  upon  so  large  a  proportion  of  the  mines  should  be 
applicable  to  all  of  the  mines  of  the  State. 


Fig.  2.    Mines  selected  for  cooperative  investigation. 


12 


COAL   MINING   INVESTIGATIONS. 


Table  2. — Districts  into  which  the  State  has  been  divided  for  the  purpose 

of  investigation 


In- 
ves- 
ti- 

ga- 
tion 
dis- 
trict. 

Coal  bed. 

Method  of  mining. 

Counties. 

Inves- 
tigation 
numbers  for 

mines 
examined. 

I 

No.  2 

Longwall 

Bureau,  LaSalle,  Grundy,  Will,  Putnam, 

No.  2 

Room-and-pillar. . . 
Room-and-pillar. . . 

Room-and-pillar. . . 
Room-and-pillar. . . 
Room-and-pillar. . . 
Room-and  pillar. . . 

Room-and-pillar. . . 

1  to  11 

II 

Jackson 

Rock  Island,    Mercer,    Warren,    McDo- 
nough,  Fulton,  Schuyler,  Brown,  Scott, 
Green,  Calhoun,  Henry,  Jersey,  Han- 

12  to  16 

III 

Nos.  1  and  2 

No.  5  (Central) .... 

No.  5  (Southern)... 

No.  6  (East  of  Du- 
Quoin  anticline). 

No.  6  (West  of  Du- 
Quoin  anticline). 

Nos.  6  and  7  (Dan- 
ville district) 

Nos.  2  and  5  (Work- 
ing two  seams) . . 

17  to  24 

IV 

Peoria,  Fulton,  Tazewell,  Logan,  Menard, 

25  to  42 

V 

Saline,  Gallatin 

43  to  49 

VI 
VII 

VIII 

JelTerson,  Perry,  Jackson,  Franklin,  Wil- 
liamson   

Sangamon,  Christian,  Moultrie,  Shelby, 
Macoupin,     Montgomery,     Madison, 
Bond,  St.  Clair,  Clinton,  Marion,  Wash- 
ington, Perry,  Randolph,  Henry 

50  to  65 

66  to  90 

91  to  97 

IX 

Bureau,  LaSalle,  Livingston,  McLean 

10,  98,  99,  100. 

For  convenience  in  reference  an  alphabetical  arrangement  by  counties 
is  given  in  Table  3. 


Table  3. — Alphabetical  arrangement  of  counties 


County 


Coal  bed 

District 

6 

VII 

1, 

2 

III 

2 

I,   IX 

1, 

2 

III 

1.  2, 

6 

III,  VII 

6 

VII 

6 

VIII 

6 

VI 

1,   2, 

0 

III,  IV 

5 

V 

1, 

2 

III 

2 

I 

1, 

2 

III 

L  2, 

6 

III,  VII 

2, 

5 

II,  VI 

6 

VI 

1, 

2 

III 

2 

I,   IX 

2 

IX 

5 

IV 

5 

IV 

6 

VII 

6 

VII 

6 

VII 

1 

2 

I 

County 


Coal  bed     District 


Bond 

Brown 

Bureau 

Calhoun . . . 
Christian.. 

Clinton 

Edgar 

Franklin. . . 

Fulton 

Gallatin . . . 

Greene 

Grundy 

Hancock . . . 

Henry 

Jackson 

Jefferson . . . 

Jersey 

LaSalle 

Livingston. 

Logan 

Macon 

Macoupin . . 
Madison . . . 

Marion 

Marshall . . . 


McDonough. 

McLean 

Menard 

Mercer 

Montgomery . 

Moultrie 

Peoria 

Perry 

Putnam 

Randolph . . . 
Rock  Island. 

St.  Clair 

Saline 

Sangamon... 

Schuyler 

Scott 

Shelby 

Stark 

Tazewell 

Vermilion . . . 

Warren 

Washington . 

Woodford 

Will 

Williamson . . 


I*  2 
2 
5 

li  2 
6 
6 
2 

5,  6 
2 
6 

1,  2 
6 
5 

2,  5 
1,  2 
1,   2 

6 
2 
5 
6 
li  2 
6 
2 
2 


III 

IX 

IV 

III 

VII 

VII 

IX 

VI,  VII 

I 

VII 

III 

VII 

V 

IV,  VII 

III 
III 

VII 

I 

IV 
VIII 

III 

VII 

I 
I 

VI 


The  collection  of  the  general  information  at  each  mine  has  been  accom- 
plished with  the  aid  of  the  following  series  of  field  notes. 


METHODS    OF    INVESTIGATION.  13 

COAL  MINING  INVESTIGATION 

Cooperative  Agreement 

Operator Date Ccal  Bed 

Address 

Supt Address 

Mine  Mgr R .  R 

Cap.  per  Day tons.  Aver,  per  Day tons. 

Tipple:  Steel  or  wood.  Cage:  Type Size 

Loading  Tracks:  No Cap 

Hoist.  Eng.:  Mfg Size Kind 

Drum:  Diam Length 

Boilers:  Type No Total  H.  P Av.  Steam  Press 

Elec.  Generator:  K.  W D.  C— A.  C.  Volt 

Compressors:  No Size Press 

Fan:  Type Diam Width 

How  Driven Blowing,  Exhaust,  Water-gage 

Magazine:  Const Dist.  from  nearest  bldg 

Surface  Plant:  Plan Const 

Surf,  fire  protec 

Hoist,  shaft:  Depth Size No.  Compts 

Lining Cost  of  sinking 

Air  shaft:  Depth Size No.  Compts 

Lining Cost  of  sinking 

No.  employees:  Surf Underground 

Nationality:  

Ownership:  Surface,  leased Fee 

Coal,  leased Fee 

Acreage  aband Under  devel Unmined 

Life  of  mine:  Past Future 

Improvements  Underway 


Trade  name  of  coal Market . . . 

Selling  agts Fit.  rates. 

Show  on  mine  map  land  leased  and  held  in  fee. 


Town Mine Co. 

A.— SURFACE  SHEET.    Collector No. 


14 


COAL   MINING   INVESTIGATIONS. 


COAL  MINING  INVESTIGATION 
Cooperative  Agreement 


Haulage  System 

Cars:  Wt Cap Ties:  Kind  of  wood Size 

-Rail  wt.:  Entry Room Track  gage 

System  of  mining 

Entry  width:  Main Cross Room 

Entry  length:  Main Cross Room 

Coal  recov.  %:  1st  Working Drawing  pillars Total 

Time  of  drawing  pillars:  Room 

Entry Sketch   method 

Entry  pillar  width:  Main Cross Room 

Barrier  pillar  width:  Main Cross 

Rooms:  No Width Length 

Coal  cutters:  Type Mfg Cut 

Does  coal  stick  to  roof? 

Does  immediate  roof  fall  in  rooms? 

Do  pieces  get  loaded  with  coal? 

Floor:  Soft,  hard,  smooth,  rough? Does  coal  stick  to  floor? 

Do  pieces  get  loaded  with  coal? 

Gas:  Found  in— roof ,  coal,  floor,  rooms,  entries 

Quantity Max.  in  ret 

Section. 


Ft.       No.     Desc.     In. 


.Max. 


Min. 


Coal  seam,  Thick:  Av 

Vert.  ht.  to  nearest  workable  coal 

Vert,  depth  to  nearest  workable  coal 

Dip Direction 

Cleat Direction 

Detailed  description  of  physical  properties  and  variability  of  roof  and 
floor  materials  and  coal  peculiarities 


Collector 

B.— UNDERGROUND  SHEET.     Nameofseam No. 


METHODS    OF    INVESTIGATION. 


15 


COAL  MINING  INVESTIGATION 

Cooperative  Agreement 

Mine  water:  Gals,  per  min Pump  driven  by. 

Charac.  of  water 

Occurrence:  At  faces At  shaft 

At  special  sections 

Humidifying:  Where  and  how:  


Cars:  How  often Gals,  per  24  hrs.  . . . 

Hose:  How  often Gals,  per  24  hrs.  . . . 

Sprays:  How  often Gals,  per  24  hrs.  . . . 

Dist.  between  sprays Dist.  wet  from  face 

Exhaust  steam:  Method 


Effect:  On  roof 

On  men 

Calcium  chloride:  How  applied 

Shale  dust:  How  applied 

Where  obtained 

Results 

Is  present  method  considered  efficient? 


Expense  of  installation . 


Expense  to  maintain. 


Place. 

Time. 

Dry  B. 

Wet  B. 

Barom. 

Quant.  Air 

Surface  on  entering 

Surface  on  exit 

Station 

Station 

Station 

Station 

Collector 

C— HUMIDITY  SHEET. 


16 


COAL    MINING    INVESTIGATIONS. 


COAL  MINING  INVESTIGATION 

Cooperative  Agreement 


Entry  timbers:  Life. . . 
Sketch, 


Preservatives:  Kind Cost 

How  applied 

Treated  timber:  Cost Life 

Untreated  timber:  Cost Life 

Steel  timbers:  Cost  to  install 

Cost  to  maintain 

Room  Props.:  Length Cross  Section . . 

First  cost Life 

No.  per  100  sq.  ft.  of  room Per  ton  of  coal 

Size  of  < 


caps. 


Accidents  from  falls  of  roof:  No.  fatal in years. 

No.  non-fatal in years. 

Sketch  typical  room:  Show  length,  width,  positions  oi  track,  props,  amount  of  gob,  distance  from  nearest 
row  of  props  to  room  face. 


Collector 

D.— TIMBERING  SHEET. 


No. 


METHODS    OF    INVESTIGATION.  17 

COAL  MINING  INVESTIGATION 
C coper ative  Agreement 


Explosives:  Kind Size Lbs.  per  charge 

Lbs.  per  ton  of  coal Cost  per  ton  of  coal 

Tamping  material:  Kind Furnished  to  miners? 

Where  obtained? 

Holes:  Length Diam 

Tamping  bar Needle 

How  fired:  Squib,  fuse,  fuse  and  cap,  electric  detonators 

How  stored 


How  thawed. 


How  delivered:  To  mines. 
To  miners. 


Hydraulic  device:  Name,  description  and  results. 


Results  of  blasting:  Frequency  of  windy  shot  s 

Of  blown-out  shots Of  mine  fires 

Per  cent  of  lump  coal 

Effects  of  blasting  on  roof 

Accidents  from  blasting:  No.  fatal in years 

No.  non-fatal in years 

Shot-firers:  No Holes  per  man 

Fire  runners:  No 

Sketch  blasting  method:  Show  position,  length  .inclination  of  holes.    Givefronl  and  side  elev.  and  plan 


Collector 

E.— BLASTING  SHEET.  No 


-2    M    I 


18  COAL    MINING    INVESTIGATIONS. 

COAL  MINING  INVESTIGATION 

Cooperative  Agreement 

1.  Assigned  cause  of  fire 

2.  Acreage  affected 

3.  Amount  of  coal  lost 

4.  Method  of  fire  fighting 

5.  Kind  and  effectiveness  of  seals 

6.  Cost  of  fire  sealing 


Collector 

F.— MINE  FIRE  SHEET.  No. 


METHODS    OF    INVESTIGATION.  19 

COAL  MINING  INVESTIGATION 

COOPEKATIVE  AGBEEMENT 

Acreage  affected 

Coal  lost:  Amount % 

Overburden:  Ht Wt.  per  sq.  ft 

Nature 

Cost  of  checking  squeeze 

Coal  extracted  previous  to  squeeze 

Correlate  on  map  any  surface  cracks  with  workings 

Sketch  method  of  checking  squeeze,  showing  walls,  cogs,  surrounding  pillars  of  coal.    Describe  any  special 
features 


Collector 

G.— MINE  SQUEEZE  SHEET. 


20  COAL   MINING   INVESTIGATIONS. 

COAL  MINING  INVESTIGATION 

Cooperative  Agreement 

Run  of  mine  shipped:^Per  cent Price  per  ton 

Sizes        '  '       '  '     

Names     '  '     '        '      '     

Per  cent '  '     '     

Screen     '  '     '        '      '     

Bar,  Length, Inc! °    Space Width Size. 

Shaker:  Length Incl .. .°  Width 

Shakes  per  min Sizes  of  holes 

Revolving:  Length Incl °  R.  P.  M Diam 

Holes:  Shape Sizes 

Picked:  On  chute,  belt,  car No.  pickers ' 

Crusher:  Type Size Cap 

Washery :  Type 

Builder Cap 

•      A  v.  daily  tonnage Unwashed  storage  cap 

Coal  screened  when 

Hydraulic  classifiers:  No No.  compt 

Dimen Sizes  of  products 

Coarse  coal  jigs:  No Cap Strokes  per  min. 

Fine  coal  jigs:  No Cap Strokes  per  min. 

Cone  washers:  No Dimen 

Storage  cap Car  loaders 

Refuse  disposal 

Weighing  devices 

Cost  of  preparation 


Collector 

H.— PREPARATION  SHEET.  No 


METHODS    OF    INVESTIGATION. 


21 


COAL  MINING  INVESTIGATION 

Cooperative  Agreement 

Operator Date 191 

Mine Located Miles* fromf 

Location  in  mine 

Total  (vertical)  depth  from  surface  at  point  of  sampling ft 

In  describing  the  beds  and  character  of  the  members,  note  any  member  that  is  rejected  by  the  miner 
Note  all  clay  and  sulphur  partings,  whatever  their  thickness.  Exclude  from  sample  all  clay  and  sulphur 
partings  j{  inch  thick  or  over  (and  even  those  of  less  thickness  if  they  are  rejected  at  mine  or  tipple). 

Section  of  Bed  at  Point  Sampled. 


No. 

DESCRIPTION.                                         Feet. 

Inches. 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

Total 

Is  coal  wet  or  dry? 

Time  exposed hours. 

Weight gross . 

What  are  the  impurities,  and  how  do  they  occur?  . . . 


.minutes. 
net 


What  are  shipped?  

What  are  excluded  from  the  sample? 


^Direction  (N.,  NE.,  etc.). 


Coal  bed 

fNeareal  railway  station. 


Town Mine. 

Sample  No Can  No 

I.— COAL  SAMPLE  SHEET.    Sampler... 


.Co. 
.No. 


22 


COAL   MINING   INVESTIGATIONS. 


COAL  MINING  INVESTIGATION 

Cooperative  Agreement 


Mine  Name  or  No. 

mile.. 

Operator.  191 


Operator,  191 


ft   (above. 
I  below . 


.T  T. 


Sec. 


Entrance Elev 

L  ueiuw — 

Depth  to  bottom  coal ft Alt R.  R. 

Surface  Data 

A.  Topography See . 

B.  Superficial  materials (1)  Character 


(2)  Thickness (3)  EfTeet'onjnining  and  shaft-sinking,  of  former  drain- 
age lines,  underground  water  strata,  etc 


.See. 


.See. 


C.  Outcrops (1)  Character 

(2)  Structure 

(3)  Fossil  horizons See . 

Collection  No 

(4)  Evidences  of  subsidence See . 

D.  Note  collection  of  mine  maps,  drill  records  and  shaft  logs 


See  drill  record  sheet. 


E.    Notes  on  surrounding  area. 


See. 


Coal  bed  name:  Local 

Collector 

Mine 

L.— SURFACE  SHEET  (Geol.). 


.Co. 


.Survey 

...State  No. 
.Coop.  No.  . 


METHODS    OF    INVESTIGATION". 


23 


Underground  Data 


F.     Thickness  of  rock  above  bed  worked. 
(1)  Important  variations 


G.     Note  pras3nce  of  strata  having  important  effect  on  mining. 


.See.. 
...See. 


(1)  Position 

(2)  Character 

(3)  Persistence 

(4)  Other  workable  coal  beds. 


H.    Cap  rock 

(1)  Thickness 

(2)  Height  above  coal . 


I.      Immediate  roof. 
(1)  Thickness.. 


.....See.. 

(2)  Contact  with  coal 


(3)  Horizontal  variation . 


J.      Draw  slate.    (1)  Thickness. 


See. 

.(2)  Contacts  . 


(3)  Persistence. 


K.    Coal  bed:  Max Min Av inches 

(1)  Benches 

(a)  Position 


(b)  Persistence. 


See. 


(2)  Bedded  impurities,  kind,  position  in  benches,  persist- 
ence, ease  of  separation 


See. 


(3)  Irregularities  in  continuity  of  bed  (due  to  deposition, 
erosion,  or  movement) 


.  See . 


(a)  EiTect  on  mining. 


.  See . 


.See. 


Collector . 
Mine 


.Coal. 


SECTION. 

Ft. 

In.    Name 

Index 

Sym. 



State  No. 


.Co Coop.  No. 


M.— UNDERGROUND  SHEET  (Geol.). 


24  COAL    MINING    INVESTIGATIONS. 


Underground  Data  (cont'd.) 


K.    (5)  Physical  character  of  coal  in  benches . 
(a)  Relative  hardness 


( b)  Lustre 

(c)  Fracture 

(d)  Texture See . 

(6)  Impurities  in  coal,  other  than  bedded 

(a)  Kind 

(b)  Position  and  persistence 


(c)  Rejected Ease  of  separation 

, See. 

L.     Floor:  (1)  Material 

(2)  Thickness 

(3)  Variation 


(4)  Note  character,  condition,  tendency  to  heave,  relation  to  undercutting,  commercial  value 


See. 

(5)  Clay  sample  No Location 


M.    Stratigraphy 

(1)  Fossiliferous  horizons  underground. 


Collection  No '. Location . 


N.    Notes  on  effect  of  deep  drilling  in  coal  mine  areas . 


.See. 


Collector Coal |         |     State  No. 

Mine Co Coop.  No.  . 

N.— UNDERGROUND  SHEET  (Geol.). 


GEOLOGICAL    STUDIES.  25 


STUDY  OF  GEOLOGICAL  FEATURES. 


1.     COAL  RESOURCES  OF  ILLINOIS 

The  area  underlain  in  Illinois  by  coal-bearing  formations  approximates 
36,800  square  miles,  but  this  is  only  indirectly  an  index  to  the  amount 
of  coal  available  under  existing  commercial  conditions,  for  coal  must  be 
thick  enough  and  of  good  enough  quality  to  permit  profit  in  recovery,  or 
it  will  not  be  mined. 

The  production  of  Illinois  mines  in  the  calendar  year  1911,  according 
to  statistics  compiled  jointly  by  the  State  Geological  Survey  and  the 
U.  S.  Geological  Survey,  amounted  to  53,679,118  tons  valued  at  $59,- 
519,478.  The  tonnage  exceeds  that  of  1910  by  7,778,872  tons  or  16.9 
per  cent.  The  phenomenal  increase  in  production,  shown  in  fig.  1,  gives 
rise  to  conjecture  as  to  the  total  coal  remaining  and  the  number  of  years 
that  it  will  sustain  the  increasing  commercial  and  domestic  needs. 

The  first  Illinois  Geological  Survey  under  Dr.  A.  H.  Worthen  deter- 
mined that  there  were  16  different  coal  beds,  and  numbered  them  in 
order  beginning  with  the  lowest.  It  is  now  clear  that  coal  exists  at  many 
additional  horizons  in  the  Pennsylvanian  series,  but  that  the  extent  and 
thickness  of  the  beds  is  probably  unsatisfactory  except  in  the  case  of  a 
very  limited  number.  Calculations  by  Bement1  for  1909  (fiscal  year) 
indicated  that,  of  the  total  output,  Coal  Xo.  6  (Herrin,  Belleville,  etc.) 
produced  59  per  cent,  Coal  Xo.  5  (Springfield,  Earrisburg,  etc.)  yielded 
25  per  cent,  and  Coal  No.  2  (La  Salle,  Third  Vein,  Wilmington,  etc.) 
produced  12  percent.  The  small  remainder.  4  per  cent,  was  mined  from 
No.  7  (Danville),  No.  1  (Rock  Island),  and  scattering  Beams.  It  is 
clear  that  only  Nos.  6,  5,  2,  7,  and  1  are  important  producers  at  present, 
and  that  the  bulk  of  production  is  likely  to  come  more  and  more  from 
the  two  beds  first  mentioned. 

It  will  doubtless  require  many  years  and  many  changes  in  competitive 
relations  or  in  state  supervision  before  we  shall  extensively  mine  coals 
as  thin  as  24  inches,  after  the  present  manner  of  some  foreign  countries. 
Assuming,  however,  that  such  thin  coals  should  be  included  in  estimates 
of  future  reserves  the  State  Geological  Survey  in  L908  calculated  that 
the  total  remaining  coal  was  approximately  136  billion  tons.  An  estimate 
by  the  U.  S.  Geological  Survey  based  on  coals  20  inches  or  more  in 
thickness  amounted  to  240  billion  tons.  Bement  calculated,  in  1909,  on 
the  basis  of  coals  measuring  12  inches  or  more,  that  there  was  approxi- 
mately 201  billion  tons.  The  State  Geological  Survey  has  now  re-calcu- 
lated the  probable  reserves  and  is  disposed  to  think  that  there  may  be 
200  billion  tons  exceeding  two  feet  in  thickness. 

»  Bement,  A.  Bull.  Illinois  State  Geol.  Survey,  No.  14,  p.  186,  1910. 


26  COAL   MINING   INVESTIGATIONS. 

2.     SCOPE   OF   XEW   WOEK   OX   GEOLOGY   OF   THE 
COAL    FIELDS 

The  work  of  the  Geological  Survey  under  the  cooperative  investigation 
has  been  devoted  principally  to  the  careful  examination  of  surface  and 
underground  geology  at  each  of  the  one  hundred  mines  selected  as  typical. 
The  objects  of  this  work  have  been : 

To  secure  all  available  information  regarding  the  coal  resources  of  the 
State ; 

To  continue  the  investigations  of  the  character  and  quality  of  Illinois 
coal,  as  shown  by  analysis; 

To  determine  the  commercial  availability  of  clay  materials  in  typical 
coal  mines; 

To  investigate  the  problem  of  safeguarding  coal  properties  from  danger- 
ous gas,  oil,  and  water  borings. 

The  special  studies  on  the  surface  involved  the  effect  of  topography 
and  of  surface  materials,  such  as  clay,  quicksand,  etc.,  on  shaft-sinking 
and  on  surface  subsistence  due  to  mining. 

Another  phase  of  the  work  has  been  the  collection  of  all  new  drill 
records  that  could  be  secured,  and  the  study  of  these  together  With 
several  thousand  already  in  the  Survey  files.  Many  of  the  latter  had 
been  collected  in  cooperation  with  the  IT.  S.  Geological  Survey  in  1908. 

The  underground  studies  related  to  a  number  of  definite  problems 
including : 

Position,  character,  and  extent  of  cap-rock,  and  other  roof  materials  af- 
fecting mining  operations; 

Character  of  floor  materials  as  affecting  undercutting  of  coal,  and 
mine-squeeze; 

Distribution  and  character  of  iron  pyrites  (sulphur),  bone,  clay  bands, 
and  other  impurities  in  the  coal  beds; 

Character  and  probable  extent  of  faults,  rolls,  clay  veins,  and  erosion 
areas  in  the  coal  beds. 

The  schedules  "L,"  "M,"  and  "X"  (pp.  22-24)  were  used  in  collection 
of  routine  information  and  were  supplemented  by  additional  notes. 

3.     CHEMICAL    QUALITY    OF    ILLINOIS    COALS 

Since  the  character  of  a  coal  determines  its  possible  uses,  there  has 
been  a  growing  public  interest  in  learning  the  characteristics  of  Illinois 
coal,  and  all  the  various  uses  to  which  it  is  especially  adapted.    , 

Since  190G  the  Geological  Survey  has  published  bulletins  3,  4,  8,  14, 
and  16  which  relate,  in  part  at  least,  to  studies  of  the  subject  made  by 
the  Survey  in  cooperation  with  the  Department  of  Applied  Chemistry 
and  the  Engineering  Experiment  Station  at  the  University  of  Illinois.    , 

In  connection  with  the  cooperative  investigation  practically  all  of  the 
100  mines  selected,  and  a  small  additional  number,  were  sampled. accord- 
ing to  new  standards,  as  stated  below : 

A  fresh  face  which  represented  average  conditions,  as  nearly  as  possible, 
was  cleaned  by  taking  off  a  layer  of  2  or  3  inches,  after  which  all  loose 
pieces  were  removed  from  the  immediate  roof.  A  large  piece  of  oilcloth 
was  then  spread  on  the  floor,  and  a,  strip  of  coal  amounting  to  at  least 
five  pounds  to  the  foot  was  cut  down  from  top  to  bottom.     Any  .bone, 


GEOLOGICAL    STUDIES. 


27 


Fig.  3.    Coal  grinder  for  mine  sampling 


1  1  1 

.5 

<0 

*>r:i- 

§^^P  «■ 

Fig.  4.     liiille  for  reducing  mine  samples 


28  COAL    MINING    INVESTIGATIONS. 

blue-band,  sulphur,  or  other  impurity  exceeding  three-eighths  inch  in 
thickness  was  discarded,  instead  of  next  being  quartered,  as  in  some 
earlier  collections,  the  entire  sample  was  quickly  ground  to  one-eighth 
inch  size  or  smaller  in  a  special  grinder  (fig.  3).  The  coal  was  then 
reduced  repeatedly  by  means  of  a  mechanical  riffle  (fig.  4)  to  a  sample 
weighing  5  pounds,  which  was  placed  in  an  air-tight  can.  This  method 
yielded  results  which  were  more  free  from  accidental  or  personal  error 
than  any  of  our  previous  efforts. 

As  a  further  improvement,  samples  were  taken  from  three  to  six  places 
in  each  mine,  and  duplicates  were  frequently  sent  to  the  laboratory  of 
the  U.  S.  Bureau  of  Mines,  so  results  could  be  compared  with  those 
obtained  at  Urbana.  The  field  notes  were  collected  on  coal  sample 
sheet  "I"  (p.  21). 

The  laboratory  work  Avas  done  in  the  laboratory  of  the  University  of 
Illinois,  under  direction  of  Prof.  S.  W.  Parr,  by  J.  M.  Lindgren  and 
assistants,  previously  listed. 

The  analyses  yielded  valuable  results  regarding  the  accuracy  of  sam- 
pling and  analytical  methods,  and  supplied  new  data  as  to  moisture,  ash, 
calcium  carbonate,  volatile  matter,  fixed  carbon,  and  calorific  value  of 
the  coals.  The  first  report  by  Professor  Parr  is  nearly  ready  for  publi- 
cation, and  others  will  follow. 

4.     UTILIZATION    OF    CLAY    MATERIALS    OF    COAL 

MINES 

The  roof  shales  and  the  under-clays  at  many  Illinois  mines  give 
promise  of  being  usable  in  the  manufacture  of  fireclay  products,  paving- 
blocks,  or  other  clay  wares.  Already  the  clay  materials  at  a  few  of  the 
mines  are  so  utilized.  It  seems  probable  that  a  large  auxiliary  industry 
can  be  created  at  many  mines,  where  clay  materials  can  be  produced 
economically,  and  where  fuel  and  transportation  facilities  are  already 
at  hand. 

As  a  part  of  the  cooperative  investigation  the  Geological  Survey  under- 
took to  secure  samples  from  about  30  promising  mines  which  represent 
the  various  districts.  The  Ceramics  Department  at  the  University  of 
Illinois  is  contributing  a  thorough  test  and  report  on  the  samples. 

5.     SAFEGUARDS  OF   GAS  WELLS  AND   OIL  WELLS  IN 
THE    COAL    FIELDS 

There  have  been  numerous  instances  throughout  the  country,  in  which 
gas,  oil,  and  water  from  active  and  abandoned  wells  have  been  released 
in  coal  mines  with  disastrous  results.  Many  states  have  legislated  with 
a  view  of  providing  safeguards  or  restrictions  so  as  to  minimize  the 
danger.  Many  if  not  all  of  the  present  laws  are  inadequate,  and  the 
subject  is  a  live  one  throughout  the  country. 


GEOLOGICAL    STUDIES.  29 

As  a  part  of  the  cooperative  investigation  the  Geological  Survey  under- 
took to  study  the  matter  carefully  and  to  recommend  means  of  meeting 
the  problem.  Already  a  committee  of  the  various  State  Geologists  is  at 
work,  in  cooperation  with  the  U.  S.  Bureau  of  Mines,  and  representative 
coal  and  oil  operators. 

As,  early  as  possible  a  report  with  recommendations  will  be  presented, 
and  all  states  concerned  will  be  urged  to  adopt  uniform  legislation  on 
the  subject. 


30  COAL   MINING    INVESTIGATIONS. 


STUDY  OF  MINING  METHODS. 


The  conditions  under  which  coal  is  mined  in  Illinois  have  been  studied 

under  the  following  headings : 

1.  Systems  of  mining 

2.  Blasting  and  explosives 

3.  Timbering 

4.  Haulage 

5.  Hoisting 

6.  Ventilation  and  mine  gases 

7.  Mine    stoppings 

8.  Humidity  of  mine  air 

9.  Coal   dust 

10.  Machine    cuttings 

11.  Preparation   of  coal  for  market. 

1.     SYSTEMS    OF    MINING 

Since  the  topography  of  Illinois  is  as  a  rule  flat,  and  the  coal  seams  lie 
nearly  horizontal,  the  coal  in  practically  all  the  shipping  mines  is  reached 
by  shafts,  the  location  of  which  is  determined  mainly  by  the  shape  of 
the  properties  and  by  the  shipping  facilities. 

The  plan  of  underground  development  for  any  particular  mine  should 
be  based  on  the  careful  consideration  of  such  important  factors  as : 

Character,  thickness,  and  weight  of  overburden 

Nature  of  roof  and   floor 

Inclination  and  thickness  of  the  seam 

Physical   character   of  the   coal 

Presence  and  pressure  of  gas  in  the  seam 

Danger  of  spontaneous  combustion,  etc. 

Failure  to  consider  these  factors  and  the  desire  for  an  immediate 
return  on  the  investment,  have  often  resulted  in  the  abandonment  of 
large  areas  in  many  mines  because  of  squeezes,  fires,  etc. ;  lives  have  been 
lost;  and  heavy  expense  has  been  incurred  in  the  attempt  to  repair  the 
damages. 

One  of  the  objects,  therefore,  of  the  cooperative  investigation  has  been 
to  study  the  prevalent  mining  methods:  room-and-pillar  (and  its  modifi- 
cation known  as  the  panel  system),  long  wall,  and  stripping,  in  order  to 
compare  the  practice  under  different  conditions  in  the  mines  of  the 
State  and  to  note  such  modifications  of  each  method  as  make  the  mining 
successful. 

Data  on  systems  of  mining  as  shown  on  field-note  sheets  "A,"  "B," 
"D,"  and  "E"  (pages  13,  14,  16  and  17)  have  been  collected  from  each 
of  the  100  mines  visited. 


MINING    METHODS. 


31 


For  information  of  readers  who  may  not  be  familiar  with  the  mining 
practice  in  Illinois  there  is  given  in  Appendix  "B"  (p.  )  a  general 
description  of  the  fundamental  systems  of  mining  which  prevail. 


2.     BLASTING    AND   EXPLOSIVES 

According  to  the  Illinois  Coal  Report  for  1911,  during  the  eleven 
years  from  1901  to  1911  inclusive,  14.4  per  cent  of  all  fatal  accidents 
have  been  due  to  blasting.  Blasting  has  caused  also  a  large  number  of 
explosions  and  mine  fires.  Nearly  all  of  the  accidents  from  explosions 
may  be  attributed  to  the  careless  or  excessive  use  of  powder.  During 
1910  and  1911  the  number  of  fatal  accidents  from  the  use  of  explosives 
in  Illinois  was  only  5.3  per  cent  of  all  the  fatal  accidents.  Thus  it 
appears  that  the  average  for  the  past  eleven  years  as  noted  above  is 
unnecessarily  high  and  that  the  subject  is  worthy  of  careful  study. 

The  data  that  have  been  collected  on  blasting  methods  in  Illinois  may 
be  seen  by  reference  to  the  "E"  sheet  of  the  field  notes  (p.  17).  At 
each  mine  visited,  a  general  sketch  was  made  of  the  method  of  placing 
the  holes  (fig.  5). 


Fig.  5.    Sketch  showing  arrangement  of  shots  in  coal  face 

In  addition  to  the  general  information  on  the  blasting  methods,  ;i 
special  investigation  has  been  made  of  the  field  use  of  "permissible 
explosives"  and  their  adaptability  to  Illinois  mining  conditions. 


3.     TIMBERING 

Falls  of  roof  and  coal  arc  causes  of  50  per  cent  of  the  total  accidents 
in  mines.  One  of  the  means  of  lessen ing  them  is  the  intelligent  use  of 
timber.      Inasmuch   as, good    mine   t milter   is   becoming  more  scarce  and 


32  COAL    MINING   INVESTIGATIONS. 

expensive  every  3rear,  the  method  of  timbering  adapted  for  any  mine  is 
an  important  item  not  only  of  mine  safety  but  also  of  the  operating 
expense. 


Fig.  6.    Sketch  of  typicaljoom  showing  location  of  timber 

There  are  two  main  reasons  for  using  timber  in  mines :  to  control  roof 
subsidence  during  coal  extraction,  and,  secondarily,  to  give  miners  warn- 
ing of  approaching  roof  falls.    Timbering  methods  in  Illinois  have  been 


MINING    METHODS. 


33 


studied  with  these  facts  in  mind,  and  information  has  been  obtained  to 
show  the  relative  merits  of  the  various  methods,  and  the  manner  in  which 
the  timber  cost  varies  with  the  different  dimensions  of  rooms  and  pillars. 
Data  on  the  size,  cost,  and  life  of  wood,  steel,  and  concrete  timbering- 
has  been  obtained  as  shown  on  the  "D"  sheet  of  the  field  notes  (p.  16). 
Also,  a  sketch  (fig.  6)  has  been  made,  which  shows  a  typical  room  and 
the  details  of  the  timbering  method  in  each  mine  visited. 

4.     HAULAGE 

Mine-car  and  mine-locomotive  accidents  caused  over  17  per  cent  of 
the  fatalities  in  Illinois  mines  during  1911.  Because  of  this  fact,  and 
because  good  haulage  roads  are  of  prime  importance  in  the  economical 
operation  of  any  mine,  careful  attention  has  been  given  to  this  subject 
by  the  Cooperative  Investigation  and  data  have  been  collected  as  shown 
on  the  "B"  sheet  of  the  field  notes  (p.  14). 

In  137  of. the  387  shipping  mines  there  were  used  for  haulage  300 
electric  and   3   gasoline   locomotives.      Mule  haulage   was   used   in    "210 


KIND  of  HAULAGE 

SHORT 
TONS 

10 

PERCENTAGE 
20                30                 40 

50                GO 

LOCOMOTIVE 

MULE 
ROPE 

MAN 

29.310.173 

10,839,883 

2.321.010 

287.585 

60.1 

■i  4.9 
1  0.6 

Fig.  7.    Tonnage  and  percentage  of  coal  hauled  by  different  methods 

mines;  rope  haulage  in  24  mines;  and  in  7  the  cars  were  pushed  to 
the  bottom  by  men.  Fig.  1  shows  the  number  of  tons  and  Die  percentage 
of  the  total  output  of  the  State  handled  in  each  manner. 

.V      HOISTING 

In  most,  of  the  shipping  mines  in  Illinois  the  hoist  ing-plant.  is  efficieni 
and  capable  of  handling  all  the  coal  that  can  be  brought  to  the  shaft 
bottom.  Self-dumping  steel  cages  are  in  general  use.  The  new  law 
requires  that  the  means  of  ingress  and  egress  he  protected  against  fire. 
Notes  in  regard  to  hoisting  equipment  were  gathered  as  shown  on  sheet 
"A"  and  «B»  (pp.  13  aml'l  I). 

Since  a  number  of  accidents  are  reported  every  year  as  having  been 
caused  by  bad  hoist  ing-practice  or  by  defective  machinery,  the  present 
investigation  has  obtained   information  regarding:  type,  size,  and  manu- 


-3  M  I 


34 


COAL   MINING   INVESTIGATIONS. 


FORM    NO. 

(A)   MINE 

AIR 

SAMPLE 

6—662 

Rec'd, 

(Section  Chief's 

Reference) 

Bottle  No. 

Laboratory  No. 

State, 

County, 

Township, 

S.,                   T., 

R., 

Town  (distance  and  direction  from) 

Name  of  coal  bed, 

ft. 

in. 

Mine, 

Carrier, 

Room, 

Entry, 

Location  in  same, 

Operator, 

Method  of  sampling, 

Velocity, 

Area, 

Quantity, 

Barometer:  Inside, 

Outside, 

Corrected  to  sea  level : 

Inside, 

Outside, 

Bulbs:  Wet, 

Dry, 

Humidity, 

% 

Collector, 

Mailed, 

,  191 

(B)   MINE 

AIR 

SAMPLE 

(over) 

Rec'd, 

(Laboratory  Record) 

Bottle  No. 

Laboratory  No. 

State, 

County, 

Township, 

S.,                   T. 

R., 

Town  (distance  and  direction  from) 

Name  of  coal  bed, 

ft. 

in. 

Mine, 

Carrier, 

Room, 

Entry, 

Location'in  same, 

Operator, 

Method  of  sampling, 

Velocity, 

Area. 

Quantity, 

Barometer:  Inside, 

Outside, 

Corrected  to  sea  level 

:  Inside, 

Outside, 

Bulbs:  Wet, 

Dry, 

Humidity, 

% 

Collector, 

Mailed, 

,  191 

(C)   MINE 

AIR 

SAMPLE 

(Sample  Receipt) 

Designation, 

Lab.  No. 

Collector, 

Bottle  No. 

Mailed, 

,  191 

;    Received, 

,191 

Remarks : 

(Signed) 

Chief  Chemist. 

To  Mr. 

Address, 

Chem.  Lab.  No. 

Fig.  8.    Mine-air  sample  report  blank 


MINING   METHODS.  35 

facture  of  hoisting-engine;  length  and  diameter  of  drum;  type,  number, 
total  horse-power,  and  average  steam  pressure  of  boilers;  methods  of 
stoking;  speed  of  hoisting;  method  of  caging;  type  of  signaling  devices; 
kind  of  head-frame;  depth,  size,  and  lining  of  hoisting  shaft;  size,  mate- 
rial, and  life  of  guides ;  type  of  cage,  and  use  of  safety-chains. 

6.     VENTILATION    AND    MINE    GASES 

The  causes  of  mine-air  pollution  are :  respiration  of  men  and  animals ; 
gases  from  the  use  of  explosives ;  fumes  from  miners'  lamps ;  absorption 
of  oxygen  by  coal  and  pyrites;  exudation  of  gas  from  the  seam;  emana- 
tions from  excrement;  decay  of  timber  ;  coal  dust  from  mining  operations, 
etc.  These  factors  often  combine  to  impoverish  mine  air  and  render  it 
injurious  to  the  health  of  the  miners.  The  problem  of  preventing 
excessive  pollution  of  the  air  is,  therefore,  very  important. 

The  Cooperative  Investigation  lias  collected  data  on  the  following 
phases  of  the  subject  of  mine  ventilation ;  the  fan  installation ;  the 
efficiency  of  the  method  used  to  conduct  the  air  through  the  mine;  and 
the  quality  and  quantity  of  the  air  at  the  "face."  The  quality  was 
determined  by  taking  duplicate  samples  of  the  mine  air  for  analysis  in 
order  to  learn  the  kind  and  amount  of  impurities  present.  The  informa- 
tion collected  to  accompany  each  sample  is  shown  in  fig.  8. 

A  careful  investigation  of  the  occurrence  of  methane  (marsh  gas) 
has  been  carried  on  in  southern  Illinois  where  explosive  gases  are  some- 
times found  in  large  quantities.  Air  samples  from  most  of  the  mines 
in  that  territory  have  been  collected  and  the  manner  of  occurrence  of 
the  gas  noted. 

In  20  of  these  mines,  holes  21/'  inches  in  diameter  and  L0  feet  in 
length  were  bored  in  the  solid  coal.  In  these  holes  a  half-inch  galvanized 
iron  pipe  was  placed  so  that  its  end  extended  three  feel  outside  the  rib. 
The  hole  was  then  tamped  with  fire  clay.  A  pressure  gage  was  attached 
to  the  projecting  pipe  and  the  pressures  were  read  three  times  daily  by 
the  mine-manager.  Samples  of  the  borings  were  placed  immediately 
in  securely  sealed  cans  and  forwarded  to  the  Pittsburgh  laboratory,  where 
at  weekly  intervals  the  gas  emanations  were  drawn  oil',  measured  for 
volume,  and  analyzed. 

A  careful  measurement  was  also  made  of  the  exposed  coal  in  the 
workings  and  of  the  total  amount  of  gas  per  2  1  hours  in  the  return. 
This  relation  was  determined,  for  comparison,  both  in  the  new  workings 
and  the  old  workings  of  the  mine. 

7.     MINE    STOPPINGS 

'Idic  leakage  of  air  through  stoppings  is  no!  only  a  possible  source  of 
danger  to  the  safety  of  the  mine,  hut  miay  also  be  a  heavy  item  of 
expense.  Special  inquiry  has,  therefore,  been  made  into  the  cosl  and 
efficiency  of  the  stopping-  nsc<l  in  Illinois.  The  kind  of  stopping  in  use 
was  noted  at  each  mine1  visited,  also  the  life,  and  the  following  five  items 
of  cost:  initial  cost;  maintenance  charge;  renewal  repairs;  emergency 
repairs;  cost  of  leaks.  Each  of  these  items  has  been  reduced  to  an 
annual  expense,  so  as  to  give  a  definite  basis  for  the  comparison  of  one 
type  of  mine  stoppings  with  another. 


36  COAL    MINING    INVESTIGATIONS. 

In  Illinois  mines,  stoppings  are  built  of  concrete  blocks;  concrete  with 
various  aggregates ;  brick ;  pressed  gypsum  blocks,  called  Pyrobar ; 
expanded  metal  and  wood-fibre;  lumber;  lumber  and  wood-fibre;  old 
ties  and  mud  mortar;  powder  cans  and  mud  mortar;  gob,  either  tamped 
or  loose;  gob  plastered  with  lime,  mud  mortar,  or  wood-fibre. 

8.     HUMIDITY    OF    MINE    A1E 

STATEMENT    OF    THE    PROBLEM 

Experiments  have  shown  that  dry  coal  dust  mixed  with  air  may 
explode  violently  but  that  it  can  be  rendered  inert  by  efficient  moistening. 
The  moisture  in  the  mine  air  may,  also,  be  an  important  factor  in  pre- 
venting the  propagation  of  coal  dust  explosions,  because  all  the  moisture 
in  the  air  must  be  raised  from  the  temperature  of  the  mine  to  the  tem- 
perature of  the  gases  generated  by  an  initial  explosion.  Raising  the 
temperature  of  the  moisture  absorbs  heat  thus  lowering  the  temperature 
produced  by  the  initial  explosion. 

It  is  necessary  to  determine  accurately  the  relative  humidity  of  the 
mine  air  because  the  amount  of  moisture  contained  in  the  coal  dust 
depends  very  largely  upon  the  ventilating  current,  The  amount  of 
aqueous  vapor  that  can  exist  in  any  given  space  depends  directly  upon 
the  temperature;  or  as  it  is  popularly  expressed,  the  capacity  of  air  for 
carrying  moisture  increases  with  the  temperature.  For  example,  in 
winter,  when  the  outside  air  is  at  a  temperature  of  only  20  degrees  F.  it 
is  able  to  carry  very  little  moisture.  When  this  air  is  taken  into  a  mine 
and  is  heated  to  the  mine  temperature  of  05  degrees  F.  it  becomes  able 
to  carry  much  more  moisture.  To  obtain  additional  moisture  it  robs 
the  coal  dust  of  its  moisture  and  thus  renders  the  dust  more  explosible. 

Until  this  investigation  was  begun,  although  mining  men  had  accepted 
the  statement  that  the  ventilating  current  extracted  moisture  from  the 
mines  in  winter  and  deposited  moisture  in  the  mines  in  summer,  there 
was  available  no  record  of  extended  mine  humidity  readings  in  Illinois. 
Furthermore,  it  was  not  generally  realized  that  the  ventilating  current 
could  extract  as  much  moisture  from  the  coal  dust  as  it  actually  does. 

To  find  out  the  amount  of  moisture  extracted  from  or  deposited  in  a 
mine  it  is  necessary  to  know  the  amount  of  moisture  per  cubic  foot  of 
outside  air  and  the  amount  per  cubic  foot  in  the  return  ventilating 
current. 

The  United  States  Weather  Bureau  has  cooperated  with  the  Mining 
Investigation  and  has  installed  self-registering  recorders  of  temperature 
(thermographs)  and  of  humidity  (hygrographs)  at  the  following  sta- 
tions : 

La  Salle,  Illinois 
Springfield,  Illinois 
St.  Louis,  Missouri 

Similar  instruments  were  already  installed  and  in  operation  at  the 
University  station  at  ITrbana,  Illinois. 

The  Mining  Investigation  also  installed  at  Oarbondale,  Illinois,  a 
recording  thermograph  and  a  hygrograph  in  connection  with  the  equip- 
ment already  being  used  by  the  local  observer  of  the  United  State- 
Weather  Bureau. 


MINING    METHODS. 


37 


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SEAM    MO.    1 

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Fig.  9.    Approximate  coal  areas  (Bement)  showing  U.  S.  Weather  Bureau  Hygrograph  Stations  by 
circles,  and  mines  at  which  hygrometers  have  been  installed,  by  dots. 


STUDY    OF    MINE    HUMIDITY.  39 

From  the  charts  received  from  these  stations  there  is  obtained  a  con- 
tinuous record  of  the  humidity  and  temperature  of  the  outside  air  for 
the  mining  districts  of  the  State. 

INSTALLATION    OF   HYGROMETERS 

To  learn  the  moisture  content  of  mine  air  in  the  State,  twenty  mines 
(Table  4)  were  selected  so  as  to  represent  the  average  conditions.  In 
each  of  these  twenty  mines  two  hygrometers  were  installed,  one  in  the 
intake  air-course  near  the  air-shaft  and  one  in  the  return  air-course  near 
the  main  hoisting-shaft. 

Table  4  indicates  the  twenty  mines  from  which  readings  have  been 
received  daily. 

The  readings  from  the  intake  hygrometer,  which  is,  as  a  rule,  installed 
within  300  feet  of  the  intake  air-shaft,  give  the  average  amount  of 
moisture  actually  entering  the  mine  during  each  24  hours,  and  supple- 
ment the  records  from  the  U.  S.  Weather  Bureau  stations  by  giving  the 
temperature  and  humidity  conditions  of  the  outside  air  after  it  has  been 
affected  by  such  agents  as  water  in  the  intake  air-shaft  and  increase  of 
temperature  due  to  depth  of  shaft.  The  return-air  hygrometer  is  com- 
monly installed  within  500  feet  of  the  upcast  shaft  and  shows  the 
moisture  content  of  the  air  leaving  the  mine.  The  readings  of  both 
hygrometers  have  been  made  by  the  local  officials  of  the  mine  at  least 
three  times  and  in  some  eases  six  limes,  in  each  2  1  hours,  and  the  results 
have  been  forwarded  to  Urbana  for  tabulation. 

The  map  (fig.  9)  shows  the  location  of  the  United  States  Weather 
Stations  and  of  the  mines  reporting  humidity  conditions. 

The  hygrometers  installed  in  the  mines,  as  shown  in  fig.  10,  consist 
of  two  exposed  thermometers  1"?  inches  long,  calibrated  accurately  to  the 
Fahrenheit  scale  and  graduated  and  mounted  on  a  silvered  brass  back 
which  is  fastened  by  a  bent  support  to  a  wooden  frame.  The  thermome- 
ter bulbs  extend  two  inches  below  the  mounting,  thus  allowing  a  free 
circulation  of  air  around  the  bulb  and  stem.  The  bulb  of  one  of  these 
thermometers,  called  the  "wel  bulb,"  is  covered  with  a  fine  muslin  bag 
to  which  is  attached  wicking  that  extends  into  a  nickeled  water  cup. 
Water  is  thus  brought  by  capillary  attraction  to  the  hag  which  surrounds 
the  bulb  of  the  thermometer.  The  bulb  of  the  second  thermometer  is 
termed  the  "dry  bulb." 

The  operation  of  the  hygrometers  depends  upon  the  principle  of  the 
latent  heat  of  vaporization,  that  is.  as  the  water  contained  in  the  muslin 
bag  of  the  "wet  hull)*'  thermometer  evaporates,  heat  is  absorbed  from  the 
mercury  and  there  is  a  consequenl  depression  of  the  mercury  in  this 
thermometer.  The  difference  between  the  readings  of  the  dry  and  the 
wet  bulb  thermometers  is  a  measure  of  the  relative  humidity  of  the  air, 
that  is,  the  amount  of  moisture  tin1  air  actually  carries  at  that  tempera- 
ture compared  with  the  amount  it   is  able  t<>  carry  at  that  temperature. 

The  relative  humidity  is  thus  indicated  because  the  rate  of  evaporation 
at  a  given  temperature,  and  consequently  the  amount  of  depression  of 
the  wet  bulb  thermometer,  is  dependent   on   the  degree  of  saturation  of 


40 


COAL    MINING    INVESTIGATIONS. 


STUDY    OF    MINE    HUMIDITY.  41 

aqueous  vapor,  or,  as  commonly  expressed,  on  the  amount  of  moisture 
carried  by  the  air.  When  the  difference  in  readings  between  the  dry 
and  the  wet  bulb  is  known,  the  relative  humidity  can  he  determined  from 
prepared  tables.3 

In  order  to  protect  the  hygrometers  from  breakage  in  the  mines,  a 
shelter  (fig.  10)  was  made  of  24-gage  galvanized-iron,  consisting  of  two 
cylinders  intersecting  at  a  right  angle.  The  horizontal  cylinder  is  open 
al  both  ends,  thus  allowing  a  perfect  circulation  of  air  around  the  ther- 
mometer bulbs.  'Idic  {'lids  of  the  cylinder  are  protected  by  a  screen  of 
one-quarter  inch  mesh  hardware-cloth.  In  the  vertical  cylinder  there  is 
a  similarly  protected  opening  to  allow  the  thermometers  to  be  read 
conveniently. 

The  hygrometers  are  installed  at  points  in  the  mine  where  there  is  a 
velocity  of  air  of  at  least  15  feet  per  second,  in  order  that  the  proper 
rate  of  evaporation  of  moisture  from  the  muslin  hag  may  he  obtained. 


CALCULATING    MOISTURE    CONTENT    OF    MINE    AIR 

From  an  average  of  the  daily  readings  of  the  hygrometers  there  is 
obtained  the  relative  humidity  of  the  air  entering  the  mine  from  the 
intake  air-shaft  and  that  of  the  air  passing  out  through  the  return  shaft. 

From  the  Psychrometric  Tables  there  can  be  obtained  for  any  given 
temperature  and  relative  humidity,  the  weight  of  a  cubic  foot  of  aqueous 
vapor  or,  popularly,  the  weight  of  moisture  contained  in  a  cubic  foot 
of  air. 

At  the  place  where  each  hygrometer  is  placed  the  velocity  of  the  air- 
current  is  read  with  a  standardized  anemometer  and  the  area  of  the 
air-course  is  measured  to  obtain  the  cubic  feet  per  minute  of  ail'  passing 
each   hygrometer. 

Having  obtained  the  amouni  of  air  and  the  weight  of  moisture  carried 
by  it  as  it  passes  each  hygrometer,  it  is  simply  a  matter  of  multiplication 
to  obtain  the  weight  of  water  carried  into  the  mine  and  out  of  the  mine 
each  24  hours,  and  the  number  of  gallon-  of  water  carried  by  100,000 
cubic  feet  of  the  ventilating  current. 


EXTRACTION     AMI    DEPOSITION    OF    MOISTURE    I'.V    THE    VENTILATING 

CURRENT 

The  action  of  the  aii'  in  extracting  or  depositing  moisture  as  the  rea- 
sons change  and  as  the  temperature  of  the  outside  air  and  of  the  intake 
air-current  vary  is  illustrated  by  the  diagrams  in  figs.  11,  L2,  and  13, 
platted  from  actual  readings  in  a  mine. 

In  fig.  11  "A"  shows,  in  terms  of  gallons  per  24  hours,  the  amount 
of  moisture  carried  out  of  the  mine  for  each  working  day  of  I  he  week 
beginning  Monday,   March    11,  1912,  and   "\>"  the  amount   of  moisture 


i  Marvin,  C.  F.,  Psychrometric  tables  for  obtaining  the  vapor  pressure,  relative  humidity  and 
temperature  of  the  c'ew-poitii:  Bull.  U.S.  Weather  Bureau,  No.  235!  This  bulletin  may  be  obtained 
at  a  cost  of  10  cents  by  applying  t  >  the  Director  of  the  United  states  Weather  Bureau,  Washington, 
D.  C. 


HON  our 

TUESDAY 

WEDNESDAY 

THURSDAY 

FRIO  AT 

SATURDAY 

18.000 

18,000 

HETU 

w  Air 

-CUR  ft 

EHT 

14.000 

A 

! 

*    10.000 

5 

S 

fe    8,000 

3 

6.000 

'* 

r**c 

^  _ , 

4  000 

B 

*~ 

'get 

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^ 

^ 





—  " 

.-■ 

1,009 

Moisture  in  air-current  in  winter 


in. 


0<K1 

ROM  OAT 

TUESDAY 

WEDNESDAY 

THURSDAY 

FRIDAY 

SATURDAY 

Nv 

,.+ 

>~~ 



/ 
/ 

^ 

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»~ 

000 

B 

' 

Is 

/ 
/ 

S  ' 

^ 

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^ 

/ 

A 

'*-#//( 

■cut* 

f*r 

ana 

Moisture  in  air-current  in  summer 
MONDAY  TUESDAY  WEDNESDAY  THURSDAY  FRIDAY  SATURDAY 


18,000 

A 

£f\ 

— - 

.^-. 

18,000 

!$3 

^ 

/ 

■ 

*f 

** 

*>* 

s 

*> 

/ 

/ 
/ 

B 

INT  A 

E  AIR 

CM« 

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12,000 

Moisture  in  air-current  in  spring 
Figs.  11,  12,  13.    Showing  moisture  in  air-current  in  winter,  summer  and  spring 


COAL    DUST.  43 

brought  into  the  mine  during  the  same  period.  Thus  on  Friday,  March 
15,  the  air  brought  in  4500  gallons  of  water  in  21  hours,  and  the  return 
air  carried  out  15G00  gallons,  or  11100  gallons  more  than  was  brought  in. 

This  mine  has  an  average  daily  production  of  1250  tons;  and  the 
quantity  of  air  passing  through  the  mine  averages  95000  cubic  feet 
per  minute. 

In  fig.  12  the  diagram  shows  the  amount  of  moisture  contained  in  the 
intake  air-current  "B"  and  return  air-current  "A"  for  the  week  begin- 
ning Monday,  August  12,  1912.  During  this  period  the  moisture  of  the 
intake  air  exceeded  that  of  the  return  air,  and  the  ventilating  current 
therefore  deposited  moisture  in  the  mine.  The  greatest  deposit  was  on 
Tuesday,  at  the  rate  of  4300  gallons  per  24  hours. 

In  fig.  13  the  diagram  shows  the  amount  of  moisture  carried  into  the 
mine  by  the  intake  current  "B,"  and  the  amount  carried  out  by  the 
return  current  "A"  for  the  week  beginning  Monday,  May  20,  1912. 
This  diagram  shows  that  on  Monday  the  ventilating  current  was  extract- 
ing water  from  the  mine  at  the  rate  of  4000  gallons  per  24  hours.  The 
amount  of  moisture  brought  into  the  mine  and  the  amount  carried  out 
became  equal  on  Monday,  and  afterwards  the  intake  moisture  became 
greater  than  the  return  moisture.  During  the  remainder  of  this  week, 
following  surface  temperature  changes,  the  intake  current  carried  at 
times  more,  and  at  other  times  less,  than  the  return  air-current. 

For  each  of  the  twenty  mines  in  which  hygrometers  have  been  installed, 
and  consequently  for  the  entire  State,  the  calculations  made  from  the 
hygrometer  readings  during  the  period  of  a  year  show  that  in  winter 
the  coal  dust  on  the  ribs  and  floors  loses  the  greater  part  of  its  moisture. 
This  work  will  demonstrate  the  necessity  of  humidifying  the  air  in  all 
gassy  or  dusty  mines  in  winter. 

The  methods  of  lessening  the  dangers  of  coal  dust  in  use  ai  the  present 
time,  and  which  the  Mining  Investigation  hopes  to  study  later  are: 

Sprinkling  the  floor  from  water-cars 

Introducing  exhaust  steam  into  the  intake  air-shaft 

Spraying  at  intervals  along  the  intake  air-course 

Washing  down  the  face  and  ribs  of  working-places  before  shooting 
Putting  on  the  floor  some  chemical  salt  which  will  retain  moisture. 

9.     COAL    DUST 

It  is  a  well-recognized  fact  that  dry  bituminous  coal  dust  is  inflam- 
mable or  explosive  under  certain  conditions.  Obviously,  therefore, 
methods  of  controlling  this  dust  are  of  great  importance  to  mine  safety. 
It  is  necessary,  however,  before  a  practical  and  efficient  method  may  be 
adopted  for  rendering  the  dust  of  any  mine  inert  that  accurate  data  be 
collected  on  the  quantity,  quality,  and  relative  explosibility  of  the  par- 
ticular dust  to  be  treated. 

The  Cooperative  Investigation  has  collected  samples  of  coal  dust  in 
such  a  manner  as  to  determine  the  amount  of  dust  per  unit  area,,  the 
chemical  quality,  the  fineness,  and  the  relative  explosibility  of  the  dust 
in  each  of  the  100  mines  visited.  In  the  near  future,  ibis  information 
will  be  tabulated  and  submitted  in  a  bulletin  together  with  deductions 


44  COAL    MIXING    INVESTIGATIONS. 

which  will  show  the  coal  dusts  in  Illinois  that  are  dangerous,  the  condi- 
tions of  temperature  at  which  explosions  of  the  dust  of  the  various  coals 
will  take  place,  the  pressures  that  may  he  developed  during  the  explo- 
sion in  the  laboratory,  and  the  effects  of  the  admixture  of  ash,  moisture, 
and  marsh  gas  on  the  explosibility  of  the  dusts. 

The  gathering  of  the  samples  in  the  mines  and  their  treatment  in  the 
laboratory  has  been  accomplished  according  to  the  following  methods : 

Two  kinds  of  samples  have  been  collected; 

(1)  Bib-dust  samples  have  been  taken  at  three  points  in  each  mine 
visited;  namely,  on  the  main  haulage  road,  on  the  subsidiary  haulage 
roads,  and  inside  the  last  crosscut  near  the  face  of  an  entry  or  a  room. 
These  samples  were  taken  according  to  the  following  uniform  method: 

A  chalk  line  was  drawn  from  the  mine  roof  to  the  floor.  On  one  side 
of  this  line  an  area  of  rib  was  cleaned  with  a  one-inch  varnish  brush 
from  the  top  to  the  bottom  of  the  coal  seam.  This  area  was  made  of 
sufficient  width  for  the  dust  to  fill  a  40-gram  glass  bottle.  The  material 
was  collected  on  a  sheet  of  celluloid  or  a  piece  of  clean  paper  and  trans- 
ferred to  the  bottle  which  was  then  sealed  with  a  rubber  cork.  The 
height  and  width  of  the  area  of  rib  brushed  was  measured.  Note  was 
also  made  of  the  temperature,  the  relative  humidity,  and  the  distance 
that  the  air  had  traveled  from  the  intake  to  the  point  of  sampling. 

From  these  three  samples  are  obtained : 

(a)  The  condition  of  the  rib-dust  of  the  working  places  where  the 
velocity  of  the  ventilating  current  is  low  and  where  hand-working  or 
machine-cutting,  shooting,  and  loading,  place  great  quantities  of  dust  in 
suspension; 

(b)  The  condition  of  the  rib-dust  on  the  main  and  secondary  haulage 
entries,  where  the  velocity  of  the  air-current  is  high  and,  as  a  conse- 
quence, the  finer  dust,  made  by  the  grinding  of  the  car-wheels  and  the 
pounding  of  the  feet  of  men  and  mules,  remains  in  suspension. 

(2)  Road-dust  samples  were  taken  at  two  points  in  each  mine  visited ; 
namely,  on  the  main  and  on  the  subsidiary  haulage  roads  near  the  points 
where  the  rib-dust  samples  had  been  obtained.  These  samples  are  taken 
according  to  the  following  uniform  method  :  Covering  a  distance  of 
about  100  feet  along  the  entry,  the  100  feet  being  so  chosen  that  the 
above  mentioned  rib-dust  sample  was  taken  at  approximately  the  center 
of  this  distance,  the  sampler  gathered  on  a  metal  spatula  about  one  ounce 
of  road  dust  for  each  3-foot  interval  measured  along  the  entry.  This 
material  was  placed  in  a  metal  can  having  a  capacity  of  at  least  three 
pounds. 

In  the  laboratory  these  samples  were  weighed  in  order  to  determine 
the  quantity  per  unit  area ;  they  were  subjected  to  a  proximate  analysis, 
which  shows  the  amount  of  moisture  and  the  quality  of  the  dust;  they 
were  screened  through  20-mesh,  60-mesh,  100-mesh,  and  200-mesh  sieves 
to  determine  the  fineness  under  different  mining  conditions;  and  finally 
they  were  tested  in  the  explosibility  apparatus  to  determine  the  relative 
inflammability  of  each  dust. 

This  apparatus,  which  is  described  in  detail  in  Appendix  "C"  (p.  67), 
consists  essentially  of  a  large  (1500  c.c.)  glass  retort  in  which  any  desired 


COAL    DUST. 


45 


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46  COAL    MINING    INVESTIGATIONS. 


high  temperature  may  be  maintained  by  the  passage  of  an  electric  current 
through  a  platinum  wire.  Through  the  bottom  of  the  retort  a  definite 
quantity  of  coal  dust  is  thrown  into  the  heated  atmosphere  and  against 
the  hot  platinum  wire;  and  the  outlet  for  the  resulting  explosion  is 
through  the  top  of  the  retort  where  an  attachment  determines  accurately 
the  amount  of  pressure  generated.  An  increase  in  the  amperage  of  the 
electric  current  will  raise  the  temperature  in  the  retort  and  will  cause  a 
greater  pressure  to  be  generated  by  the  explosion  of  the  coal  dust.  The 
results  of  the  tests  on  each  coal  dust  are  plotted,  using  pressure  and 
temperature  as  the  coordinate,  as  is  shown  by  example  in  fig.  14  (p.  45). 

10.     MACHINE    CUTTINGS 

From  the  very  few  tests  that  have  been  made  in  this  country  to  deter- 
mine the  amount  of  coal  dust  resulting  from  machine  and  hand  mining, 
it  appears  that  there  would  be  15,000  to  41,000  pounds  of  20-mesh  dust 
produced  per  1,000  tons  of  coal.1 

No  tests,  however,  have  heretofore  been  made  on  Illinois  coals;  and 
as  this  subject  is  of  practical  value  from  the  point  of  view  both  of  mine 
safety  and  of  the  commercial  product  of  the  mines,  the  Cooperative 
Investigation  dining  the  summer  of  1912  made  determinations  of  the 
sizes  of  the  undercuttings  at  10  mines.  The  results  of  these  tests  have 
made  possible  comparisons  of  the  amounts  of  dust  and  small  sizes  of 
coal  produced  as  between  the  different  seams,  between  machine  and  hand 
mining,  between  puncher  and  chain  machines,  and  between  the  various 
cutting  bits  in  use. 

The  following  method  was  used  in  carrying  on  this  work  at  each  mine : 
A  room  was  chosen  in  which  were  found  average  conditions  for  the  mine 
with  respect  to  hardness  of  coal,  velocity  of  ventilating  current,  width 
of  room  and  room  centers  on  the  entry,  if  the  mine  is  worked  on  the 
room-and-pillar  system.  The  floor  and  ribs  for  a  distance  of  20  feet 
from  the  face  were  swept  clear  of  the  dust  made  by  previous  work.  If 
cuttings  were  to  be  tested,  the  mining  machine  was  then  placed  in  posi- 
tion and  the  depth  of  cut  usual  in  the  mine  was  made.  The  dimensions 
of  the  face  and  of  the  cut  were  measured  precisely  and  the  cuttings  wrere 
loaded  out  and  accurately  screened  and  weighed  on  the  surface.  These 
cuttings  included  the  dust  swept  from  the  ribs  and  floor  for  a  distance 
of  20  feet  from  the  face.  The  coal  was  then  shot  down  by  the  method 
of  blasting  in  customary  use  in  the  mine,  and  the  coal  thus  gained  was 
loaded  out  and  weighed  at  the  tipple. 

All  machine  cuttings  passing  through  the  i/o-inch  screen  were  weighed 
and  quartered  down  to  a  sample  of  250  pounds,  which  was  shipped  to 
the  coal-washing  laboratory  at  Urbana,  and  there  put  through  screens 
of  the  following  meshes  per  inch:  20,  40,  60,  80,  100,  and  200.  The 
sets  of  screens  were  made  especially  for  this  work,  and  the  sizes  of 
openings  accurately  measured.  The  sizes  screened  and  weighed  at  the 
tipple  are  of  the  following  meshes  in  inches :   1%,  1%,  1,  %,  y2  and  14. 

i  Jones,  B.  F.,  Comparative  amounts  of  dust  made  in  mining:  Mines  and  Minerals,  March,  1908,  p.  397. 
Scott,  C.  E.,  Dust  made  in  mining  coal:  Mines  and  Minerals,  May,  1908,  p.  477.  Rice,  G.  S.,  Explosi- 
bility  of  coal  dust:    Bull.  U.  S.  Bureau  of  Mines,  No.  20,  p.  33, 1912. 


COAL    DUST.  47 

By  this  method  there  has  been  obtained  definite  information  as  to  the 
amount  of  coal  made  by  under-cutting,  in  each  of  the  following  sizes : 
lump  (passing  over  1%  incn  screen),  l1/^  inch,  1  inch,  %  inch,  %  inch, 
i/4  inch,  20-mesh,  40-mesh,  GO-mesh,  80-mesh,  100-mesh,  and  200-mesh. 

The  power  used  in  under-cutting  with  electric  machines  was  obtained 
from  the  records  made  by  a  Bristol's  recording  wattmeter  for  direct 
current  having  a  register  of  38  K.W.,  250  volts,  150  amperes;  together 
with  a  Weston  voltmeter  reading  to  300  volts. 

For  punching  machines  a  pressure-gage  registered  the  air  pressure,  and 
notes  were  taken  on  the  size  of  delivery-pipe,  the  length  of  strokes,  the 
number  of  strokes  per  minute,  and  the  diameter  of  cylinder. 

11.     PREPARATION    OF    COAL    FOR    MARKET 

Because  of  keen  competition,  both  within  the  State  and  with  adjoin- 
ing states,  a  large  amount  of  work  is  considered  necessary  in  order  to 
prepare  Illinois  coal  for  market.  This  preparation  consists  both  of 
removing  the  impurities,  and  of  dividing  the  product  into  many  different 
sizes.  Most  of  the  shale  and  "sulphur"  is  removed  by  hand-picking  by 
the  miners  at  the  "face,"  but  this  is  often  supplemented  by  pickers  in 
the  tipple  or  on  the  railroad  cars.  The  sizing  is  accomplished  by  screen- 
ing equipment  which  is  provided  in  nearly  all  tipples,  and  in  some  cases 
a  re-screening  plant  is  used  for  separating  the  smaller  sizes.  At  the 
present  time  there  are  35  operating,  commercial  washeries. 

A  large  amount  of  data  has  been  obtained  to  show  the  meihocls, 
results,  and  costs  of  the  preparation  of  the  coal  (p.  20)  and  of  the 
washing  of  the  coal  (p.  20).  Complete  data  on  the  wet  sizing  of 
coal,  however,  has  not  been  obtained  by  the  Cooperative  Investigation 
as  this  subject  is  being  treated  in  a  bulletin  of  the  Engineering  Expe- 
riment Station,  University  of  Illinois. 


48  COAL    MINING    INVESTIGATIONS. 


APPENDIX  A. 


GEOLOGY  OF  THE  ILLINOIS  COAL  FIELDS. 


IXTItODUCTlOX 

The  following  geological  review  is  presented  because  the  coal  publica- 
tions by  the  Geological  Survey  are  almost  entirely  out  of  print,  and  the 
new  cooperative  results  are  not  yet  ready  in  final  form. 

In  the  future,  bulletins  on  coal  resources  and  mining  practices  will 
be  published  for  each  of  the  nine  districts  into  which  the  State  was 
divided  for  the  Cooperative  Investigation.  Later,  a  summary  report 
on  the  Illinois  coal  fields  will  be  furnished  by  the  Survey  as  a  part  of 
the   cooperative  work. 

THE    COAL-BEARING    AEEA 

The  occurrence  of  coal  in  Illinois  is  limited  to  the  area  of  the  Penn- 
sylvanian  or  coal-measures  series,  as  shown  by  fig.  15.  Even  within 
the  indicated  area  the  coal  is  not  everywhere  present  in  workable  thick- 
ness and  quality.  The  region  which  is  certainly  barren  lies  outside 
of  the  Pennsylvanian  boundary  in  northern,  western,  and  southern 
Illinois. 

The  coal  formations  underlie  part  or  all  of  86  counties,  including 
approximately  36,800  square  miles  or  about  65  per  cent  of  the  entire 
State.  The  area  underlain  by  bituminous  coal  is  greater  in  Illinois 
than  in  any  other  state  of  the  Union.  The  productive  area  along  the 
eastern  and  southeastern  borders  of  the  State  extends  into  Indiana  and 
Kentucky,  and  the  fields  of  the  three  states  comprise  the  Eastern  Inte- 
rior Field.  Probably  this  coal  area  at  one  time  was  continuous  with 
that  of  Michigan  and  with  the  Western  Interior  Field  which  lies  west 
of  the  Mississippi,  but  the  wearing  away  of  the  rocks  by  surface  erosion 
has   separated    the   neighboring  areas. 

THE    COAL-BEARIXG    FORMATIONS 

The  coals  of  Illinois  exist  as  wide-spread  beds  or  as  local  pockets 
among  layers  of  shale,  sandstone,  and  limestone  which  together  make 
up  the  Pennsylvanian  series.     There  are  five  coals  known  to  be  impor- 


>  t v ;  " .  >^ j^w ' n cio n  — rjc,  -nL^ ----;- i-^J^>^ 


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vi., 


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Fig.  15.    Map  showing  coal-measures  area  in  Illino 


GEOLOGY    OF    COAL    FIELDS.  4!) 

taut  enough  to  have  special  nanus,  and  numerous  other  beds  occur  at 
various  depths.  The  maximum  thickness  of  Pennsylvanian  rocks  is 
known  to  be  at  hast  2,200  feet,  though  it  is  not  to  be  assumed  that  a 
single  bore-hole  could  penetrate  all  of  the  various  formations  at  tic 
place  of  extreme  thickness. 

The  Pennsylvanian  series  has  been  divided  for  convenience  of  descrip- 
tion into  three  formations  which  present  different  characteristics  as  to 
time  of  deposition,  physical  composition,  and  economic  importance. 
The  divisions  from  the  bottom  upwards  are  the  Pottsville,  Carbondale, 
and  McLeansboro  formations. 

POTTSVILLE    FORMATION 

The  lowermost  formation  of  the  Pennsylvanian  in  Illinois  is  com- 
posed chiefly  of  massive  sandstones  interrupted  by  thinner  beds  of  shale 
and  beds  or  pockets  of  coal  and  fireclay.  The  prevalence  of  coarse  sand- 
stone and  locally  of  quartz  pebbles  has  led  to  the  common  name  "con- 
glomerate" or  "millstone  grit'"  for  the  Pottsville  in  Illinois,  as  in  other 
states. 

In  Illinois  this  formation  carries  plant  fragments  which  indicate, 
according  to  White,1  that  deposition  took  place  during  late  Pottsville 
time  of  the  Appalachian  coal  basins.  The  waters  probably  first  entered 
the  Illinois  area  in  the  region  of  Eardin  and  Gallatin  counties,  and 
extended  westward  and  northward,  laying  down  sandy  sediments  which,, 
locally  at  least,  are  loo  feet  thick.  The  early  sediments  are  thinner 
to  the  north  and  west  and  are  nearly  or  quite  ahsent  over  much  of  the 
State.  Massive  sandstones  in  the  Rock  Island  region  .">•"  of  Pottsville 
age,  but  later  than  the  first  sediments  of  southern  [llinois.  inc.,  Lire  a 
number  of  occurrences  of  coal  in  th"  Pottsville  in  southern  counties 
hut  at  present  they  have  no  commercial  importance,  because  of  local 
or  pockety  character.  The  No.  1  coal  of  Rock  Island  and  Mercer 
counties  is  similarly  restricted  in  area  but  is  thick'  enough  to  he  valu- 
able. The  topmost  sediments  of  the  Pottsville  in  Illinois  include  the 
Cheltenham  fireclays,  which  have  been  traced  through  (he  counties 
between  SI.  Louis  and  Rock  Island,  and  thence  eastward  to  Ottawa. 
Evidently  much  of  Illinois  was  then  at  or  near  sea  level.  The  Pottsville 
closed  just  before  the  deposition  of  Coal  No.  2.  (  Murphysboro,  La  Salle, 
Third    Vein,  etc.) 

CARBONDALE    FORM  ATHi\ 

The  second  division  of  the  Pennsylvanian  series  extends  from  the 
base  of  Coal  No.  2  up  to  the  top  of  Coal  No.  6  (Herrin,  Belleville, 
blue-band,  etc.).  It  represents  a  time  interval  comparable  to  the  Alle- 
gheny formation  of  the  eastern  states,  though  the  close  of  Allegheny 
time  in  Illinois  has  not  been  definitely  determined  and  may  include 
some  of  the  strata  Ivine-  above  the  Carbondale  as  here  defined. 


i  White,  David.,  Bull.  State  Geol.  Survey  No.  II,  p.  293,  L908. 

— 4  M  I 


50  COAL    MINING    INVESTIGATIONS. 

The  Carbondale  is  composed,  chiefly  of  shale  and  lesser  amounts  of 
sandstone,  coal,  and  limestone.  It  includes  all  the  coals  mined  for 
commercial  shipment  except  the  Rock  Island  (No.  1)  bed,  and  the 
Danville  (No.  7)  bed.  This  formation  extends  over  practically  the 
whole  coal-area,  but  its  upper  beds  are  absent  along  the  rim  and  its 
lower  beds  are  not  well  known  in  the  central  part  of  the  basin.  The 
thickness  varies  considerably,  being  from  200  to  240  feet  in  the  La  Salle 
region,  200  feet  at  Peoria,  300  feet  at  Mattoon,  and  285  feet  or  more 
in  the  southern  counties  of  the  coal  field. 

MCLEANSBORO  FORMATION 

The  topmost  division  begins  at  the  top  of  coal  No.  6  and  extends 
up  to  the  highest  Pennsylvanian  rocks  of  the  State.  With  the  exception 
of  the  Danville  coal  (No.  7)  which  at  present  is  included  in  this  forma- 
tion, there  are  no  coals  of  known  importance,  although  a  thin  bed  in 
Shelby  County  is  mined  for  local  use.  The  formation  is  dominated  by 
beds  of  shale  and  sandstone,  among  which  are  found  some  thin  lime- 
stones. The  Carlinville  (Shoal  Creek)  limestone  occurs  about  275 
feet  above  the  base  of  the  formation  and  is  persistent  over  a  considerable 
area,  The  greatest  thickness  of  the  formation  seems  to  be  in  the 
vicinity  of  Hamilton  and  White  counties  where  coal  No.  6  lies  approxi- 
mately 1000  feet  beloAv  the  surface.  A  somewhat  less  reliable  record  at 
Olney  indicates  a  depth  of  1155  feet  for  this  coal. 


THE    SPOON-SHAPED    STRUCTURAL    BASIN 

The  strata  beneath  the  surface  deposits  of  Illinois  to  a  great  extent 
lie  horizontal,  but  locally  dip  as  much  as  350  feet  to  the  mile.  When 
all  the  evidence  from  mine-shafts  and  bore  holes  is  studied  it  is  evi- 
dent that  the  State  is  an  immense  spoon-shaped  basin  with  the  tip 
in  the  extreme  northwest  counties  and  the  bowl  in  the  region  of  Wayne, 
Edwards,  Hamilton,  and  White  counties.  The  long  axis  of  the  "spoon" 
passes  near  Olney  in  Richland  County  and  Lovington  in  Moultrie 
County,  and  the  dip  in  the  central  part  of  the  basin  towards  this  axis 
is,  commonly  as  low  as  10  feet  per  mile. 

Thus,  an  east-west  section  from  Springfield  eastward  to  Cerro  Gordo 
in  Piatt  County  has  a  dip  of  300  feet  in  50  miles  or  6  feet  per  mile. 
Similarly,  the  dip  eastward  from  Iuka  in  Marion  County  to  Olney  in 
Richland  County  is  400  feet  in  40  miles  or  10  feet  per  mile. 

The  warping  of  the  strata  along  the  southwestern  and  southern  rim 
of  the  basin  has  been  much  more  pronounced  and  has  been  somewhat 
relieved  by  the  Shawneetown  fault,  which  extends  as  a  narrow  belt  from 
western  Kentucky  into  Illinois  at  Shawneetown  and  has  been  traced  at 
least  15  miles  farther  west.  This  fault  causes  the  strata  on  the  north 
to  be  about  1400  feet  lower  than  those  on  the  south.  North  of  the  fault 
and  along  the  border  of  the  active  coal  field,  the  dip  from  Cottage  Grove 
in  Saline  County  northward  to  Eldorado  averages  115  feet  per  mile. 
Similarly  from  Marion  northward  to  West  Frankfort  it  averages  50  feet 


Via.  16.    Map  showing  production  of  coal,  calendar  year,  L911.    (l)  Over  0,000,000  short  ions;  (2)  over  5,000,oo<); 
(3)  3,000,000  to 5,000,000;  (4)  1,000,000  to  3,000,000;  (5)  loo, ()()()  to  1,000,000;  (6)  under  100,000. 


GEOLOGY  OF  COAL  FIELDS.  51 

per  mile  and  locally  is  double  this  amount.  In  the  hills  5  miles  north- 
west of  Murphysboro  the  dip  is  eastward  at  a  rate  of  350  feet  per  mile. 
The  same  pilch  exists  also  in  the  area  one  mile  east  of  Du  Quoin. 

Although  the  Illinois  basin  is  approximately  spoon-shaped  there  are 
minor  folds  and  terrace-like  flats  on  the  flanks.  The  most  notable  is 
the  La  Salle  anticline,  which  is  pronounced  at  La  Salle  and  also  in  the 
oil  fields  of  Clarke  Crawford,  and  Lawrence  counties.  Doubtless  it 
extends  as  a  persistent  feature  with  a  rather  uniform  direction  between 
these  distant  areas.  The  west  side,  facing  the  axis  of  the  basin,  is  much 
steeper  than  the  east  flank.  Another  pronounced  anticline  has  been 
traced  from  the  region  5  miles  west  of  Murphysboro  to  Du  Quoin  and 
thence  northward  to  Centralia  and  Sandoval.  This  Du  Quoin  anticline 
is  also  steeper  on  the  side  facing  the  axis  of  the  basin,  in  this  case  the 
east  side.  Folds  and  faults  of  appreciable  size  other  than  those  men- 
tioned have  been  discovered,  and  doubtless  they  will  be  found  to  be 
numerous,  as  detailed  surveys  proceed. 

The  structural  relations  in  Illinois  arc  on  the  whole  unusually  favor- 
able to  coal-mining.  The  first  effect  is  of  course  to  make  the  coal 
around  the  border  of  the  field  more  easily  available  than  that  in  the 
deeper  portion,  but  the  extreme  depth  necessary  to  reach  the  most 
important  coal  (No.  6,  Herrin,  blue-band)  probably  will  not  greatly 
exceed  1000  feet,  and  the  shaft  at  Assumption  is  already  operating 
successfully  to  approximately  this  depth. 

MINING    CENTERS    AND    DISTRICTS 

The  following  notes,  in  part  repeated  Prom  Bulletin  No.  II.  relate  to 
important  geographical  district-  or  mining  centers  recognized  by  the 
public.      Relative   productions    for    the    calendar   year    1011    are    shown 

on    fig.    10. 

WILLIAMSON,    FRANKLIN,    AM)    PERRY    COUNTIFS 

Williamson  County  led  the  production  of  the  State  for  mil  with 
more  than  6,600,000  tons.  The  coal  is  similar  to  that  in  Franklin 
County  and'  in  the  eastern  part  of  Perry  County,  and  has  a  rapidly 
growing  market.  The  producing  bed  is  the  No.  (I  or  blue-band  coal 
(Herrin,  Belleville,  etc.)  which  is  from  5  to  10  feet  thick,  averaging 
9  feet  over  a  large  area.  The  top  coal,  about  £0  inches  thick,  is  com- 
monly left  to  support  the  shale  roof,  and  locally  is  withdrawn  after  the 
rooms  have  been  mined  out.  The  ffblue-band"  is  a  clay  or  shale  parting 
from  1  to  2  inches  thick,  and  about  20  inches  above  the  floor. 

There  is  a  general  northeast  dip,  amounting  io  60  feet  per  mile  in 
the  central  part  of  the  county.  Local  faults  occur,  in  places  with  20 
to  30  feet  displacement.  The  bed  outcrops  near  Marion,  but  elsewhere 
is  reached  by  shafts  from  100  to  200  feet  deep. 

There  is  no  sharp  line  between  this  field  and  its  neighbors.  The  same 
coal  is  mined  in  Perry  and  Franklin  counties  and  to  the  cast,  It 
maintains   some   uniformity   in    physical    character    and    thickness,   but 


52  COAL    MIXING    INVESTIGATIONS. 

varies  from  place  to  place  in  fuel  value.  At  Du  Quoin  the  coal  is 
nearly  horizontal,  hut  east  of  town  it  clips  rapidly  and  becomes  thicker 
and  somewhat  better  in  quality. 

SANGAMON,    LOGAN,    MACON,    AND    MENARD    COUNTIES 

The  Springfield,  district,  extending  into  several  adjoining  counties, 
has  long  been  one  of  the  most  important.  Sangamon  County  produced 
more  than  5,000,000  tons  in  1911. 

The  coal  of  the  district  is  commonly  known  as  No.  5  or  the  "Spring- 
field" coal,  though  in  the  region  south  of  Chatham,  No.  6  only  is  mined. 
Xo.  5  is  cut  by  numerous  vertical  clay  veins,  from  a  few  inches  to  four 
feet  in  thickness,  and  lacks  the  fiblue-band"  which  characteristically 
occurs  near  the  floor  of  No.  G.  Both  beds  may  have  a  limestone  cap-rock 
within  a  few  feet  of  the  coal.  No.  5  lies  about  250  feet  below  the 
surface  at  Springfield  and  GOO  feet  at  Decatur  on  the  east.  The  average 
thickness  is  a  little  less  than  G  feet  at  Springfield  and  about  4.5  feet 
at  Decatur.  There  are  three  higher  coals,  all  too  thin  to  be  mined  at 
present,  and  lying  respectively  50,  100,  and  175  feet  above  No.  5.  There 
are  likewise  several  coals  below  No.  5,  but  drilling  has  not  yet  deter- 
mined their  commercial  values. 

CHRISTIAN,    MACOCTIN,     MONTGOMERY,    AND     MADISON     COUNTIES 

The  district  extending  from  St.  Louis  nearly  to  Springfield  and 
operating  in  coal  No.  G  is  one  of  the  largest  producers  of  the  State.  The 
four  counties  named  above  had  an  output  in  1911  of  about  eleven  and 
one-half  million  tons,  of  which  Macoupin  alone  produced  4,G88,000  tons. 

The  coal  varies  considerably  in  depth  and  thickness  in  the  counties 
mentioned.  In  Christian  County  it  ranges  in  depth  from  340  feet  at 
Ldinburg  to  735  feet  at  Pana,  and  varies  in  thickness  from  6  to  8  feet. 
In  Montgomery  County,  the  depth  varies  from  50  to  G50  feet  and  the 
thickness  from  8  to  8V2  feet.  In  Macoupin  County,  the  depth  at  Benld 
is  350  feet  and  the  thickness  8  feet,  and  at  Staunton  the  depth  is  290 
feet  and  the  thickness  7%  feet.  In  Madison  County  the  depth  is  100 
to  325  feet  and  the  thickness  5  to  7  feet. 

ST.    CLAIR,    CLINTON,    MARION,    RANDOLPH,     WASHINGTON,    AND 
JEEFERSON    COUNTIES 

St.  Clair  has  long  been  one  of  the  important  coal  producers  of  the 
State.  In  the  calendar  }-ear  1911,  it  produced  approximately  4,000,000 
tons. 

This  district,  known  as  the  Belleville  district,  is  not  set  off  sharply 
from  its  neighbors,  since  the  same  coal  bed  is  mined  under  similar 
conditions  in  adjoining  counties.  It  is  the  "blue-band"  seam  (No.  G), 
with  a  parting  near  the  base,  and  a  limestone  cap-rock,  usually  above 
the  slate,  but  in  some  places  directly  overlying  the  coal  itself. 

The  coal  outcrops  along  the  western  side  of  St.  Clair  and  Randolph 
counties  and  dips  eastward  from  10  to  20  feet  per  mile.     Local  varia- 


MINING    CENTERS    AND   DISTRICTS.  53 

tions  are  frequent,  and  faults  of  6  feet  displacement  have  been  observed; 
but  the  general  conditions  are  uniform.  The  depth  varies  from  the 
outcrop  to  approximately  400  feet  at  Breese,  and  300  feet  at  Coulter- 
ville.  Farther  east  it  has  a  depth  of  425  feet  at  Nashville,  865  feet  at 
Mt.  Vernon,  600  to  680  feet  at  Sandoval  and  Centralia,  and  880  feet 
at  Kinmundy.  Throughout  this  entire  territory,  the  coal  ranges  in 
thickness  from  5%  to  9  feet,  and  commonly  averages  between  6  and  7 
feet.  As  to  quality,  analyses  of  face  samples  indicate  considerable 
irregular  variation. 

VERMILION    COUNTY 

During  the  calendar  year  1911,  Vermilion  County  produced  3,385,000 
tons.  This  has  long  been  an  important  area  shipping  principally  to 
the  Chicago  market. 

There  are  three  persistent  coal  seams,  two  of  which  are  worked.  The 
top  or  Danville  bed  (No.  7)  appears  west  of  Vermilion  River,  and  is 
mined  along  the  outcrop  and  by  shafts  from  75  to  200  feet  deep.  It  is 
about  6  feet  thick  around  Danville  but  thins  to  about  3  feet  ten  miles 
further  south.  A  band  of  bone  or  clay,  lying  20  inches  above  the  floor, 
occurs  in  some  of  the  sections. 

The  Grape  Creek  coal  (No.  6)  lies  from  20  to  80  feet  below  the 
Danville  and  is  more  important.  Tt  becomes  thicker  southward  from 
Danville,  and  covers  many  square  miles  with  a  thickness  of  from  6  to  9 
feet.  A  band  of  shale  or  sulphur  commonly  occurs  about  2  feel  above 
the  floor  and  gives  rise  to  the  general  opinion  that  this  is  to  be  cor- 
related with  the  blue-band  coal  of  southern  Illinois. 

Several  borings  have  shown  a  coal  from  185  to  220  feel  below  the 
Grape  Creek,  and  measuring  from  4  to  8  feet,  but  badly  broken  by 
bands  of  shale  and  limestone. 

SALINE    AND   GALLATIN    COUNTIES 

Saline  County  production  has  had  a  rapid  increase  since  1907,  and 
in  1911  reached  3,820,410  tons.  The  production  in  Gallatin  County 
remains  from  65, 000  to  75,000  Ions  per  voir,  but  extensive  drilling 
in  1912  indicates  that  there  will  he  a  considerable  expansion  in  the 
immediate  future. 

There  are  two  seams,  Xos.  (i  and  5,  underlying  the  northern  two- 
thirds  of  Saline  and  much  of  Gallatin  counties,  each  approximately  5 
feel  thick,  and  lying  from  90  to  LOO  feet  apart  vertically.  The  upper 
bed  is  the  blue-band  coal  (No.  (i)  which  runs  west  into  Williamson  and 
north  into  White  and  Hamilton  counties.  The  lower  seam  is  free  from 
regular  hands  and  has  considerably  higher  heating  value,  though  in  this 
respect  the  upper  seam   also   is  excellent. 

The  coals  outcrop  on  the  south,  and  have  a  general  northward  dip 
of  25  to  75  feet  per  mile.  Thus,  the  coal  which  outcrops  al  Equality 
in  Gallatin  County  is  from  900  to  looo  feel  deep  in  Hamilton  County, 
25  miles  north.  Farther  northeast,  diamond-drill  records  in  the  oil 
fields  indicate  the  presence  of  the  same  coals.     An  east-wesi    fault   with 


54  COAL   MIXING   INVESTIGATIONS. 

a  down-throw  to  the  north  of  more  than  1000  feet  crosses  the  middle  of 
Saline  and  Gallatin  counties,  and  probably  is  related  to  some  minor 
faulting  in  this  district. 

FULTON    AND    PEORIA    COUNTIES 

During  the  calendar  year  1911  Fulton  County  produced  about  2,133,- 
000  tons  and  Peoria  County  1,037,000  tons,  this  being,  in  both  cases,  a 
marked  increase  over  the  production  of  the  previous  year.  Most  of 
the  coal  from  this  region  goes  to  the  northwest  beyond  the  borders 
of  the  State. 

The  principal  coal,  called  No.  5,  is  from  4  to  4%  feet  thick,  free 
from  partings,  and  dips  gently  southeast,  usually  about  five  feet  and 
locally  as  much  as  60  feet  per  mile.  Shafts  reach  the  coal  at  from  75 
to  150  feet.  In  all,  seven  beds  are  present  here  within  300  feet  of  the 
surface,  but  only  four  have  proved  thick  and  persistent  enough  to  be 
mined.  No.  1  and  No.  2  are  no  longer  worked  and  the  production  from 
Nos.  6  and  7  is  for  local  use  only. 

LA  SALLE,  BUREAU,  PUTNAM,  MARSHALL  AND  WOODFORD  COUNTIES 

The  La  Salle  or  Northern  district  yields  coal  chiefly  by  long  wall 
mining  from  seam  No.  2  or  the  "Third  A^ein."  The  production  from 
La  Salle  County  has  been  constant  for  several  years  at  about  1,600,000 
tons.  Approximately  this  amount  was  mined  in  Bureau  County  during 
the  calendar  year  1911,  while  Putnam  produced  772,000  tons. 

The  coal  averages  about  3  feet  in  thickness,  and  is  blocky  and  of  good 
quality.  It  is  reached  by  shafts  from  125  to  530  feet  deep.  About  140 
feet  above  No.  2  lies  the  so-called  No.  5  or  "Second  Vein."  Forty 
feet  above  No.  5  lies  the  No.  7  or  the  "First  Vein."  It  is  shipped 
almost  entirely  to  the  west  and  northwest,  and  a  comparatively  small 
part  of  it  reaches  the  Chicago  market,  , 

GRUNDY   AND   WILL   COUNTIES 

The  Wilmington  field  of  Grundy  and  Will  counties  produced  in  1911 
approximately  1,000,000  tons.  The  general  conditions  are  almost 
identical  to  those  in  the  district  last  described,  except  that  the  coal  lies 
between  70  and  200  feet  beneath  the  surface,  and  is  reached  by  com- 
paratively shallow  shafts.  The  thickness  averages  36  to  39  inches  and 
mining  is  by  the  longwall  method. 

THE   WESTERN    FIELD 

The  counties  along  the  western  edge  of  the  State  are  underlain  by 
coals  Nos.  1  and  2  which  have  been  traced  from  La  Salle  and  Kock 
Island  on  the  north  to  Murphysboro  on  the  south. 

No.  1  coal  is  mined  extensively  in  Rock  Island  and  Mercer  counties 
which  together  produced  nearly  one-half  million  tons  in  1911.  This 
coal  occurs  in  restricted  areas  quite  unlike  the  upper,  wide-spread  coals 
of  the  State. 


MIXING    CENTERS    AND    DISTRICTS.  55 

The  mining  in  No.  2  coal,  along  the  western  field,  is  chiefly  at  coun- 
try banks  with  the  exception  of  that  in  Jackson  County  where  the 
famous  "Big  Muddy"  coal  is  mined  from  this  seam.  This  county 
produced  687,000  tons  in  1911,  of  which  a  major  part  was  from  the 
No.  2  bed  at  Murphysboro  and  vicinity.  It  is  shipped  mostly  to  the 
region  south  and  southeast  of  Cairo  but  in  part  is  sent  to  Chicago 
where  it  competes  with  "Youghiogheny." 

The  No.  2  coal  is  divided  into  two  beds,  each  of  which  has  been 
mined  extensively.  The  beds  are  separated  by  shale  which  varies  in 
thickness  from  15  inches  to  20  or  even  35  feet.  The  coal  is  reached  by 
shafts  from  100  to  150  feet  deep  and  is  mined  by  the  room-and-pillar 
method. 


56  COAL    MINING    INVESTIGATIONS. 


CHEMICAL  CHARACTER  OF  ILLINOIS  COAL. 


It  has  Long  been  held  that  the  various  grades  of  coal  have  resulted 
from  the  decomposition  and  natural  distillation  of  vegetal  matter, 
buried  under  later  sediments.  At  various  stages  in  the  process  the 
material    is  classed   as 

Peat 

Lignite 

Bituminous  coal 

Semi-bituminous  coal 

Anthracite  coal. 

Study  of  the  chemistry  of  Illinois  coal  has  heen  difficult  both  for  the 
specialists  who  have  heen  engaged,  and  for  the  reading  public  which 
attempts  to  follow  the  progress  of  investigations.  There  has  been 
rapid  change  in  the  viewpoint  of  chemists,  and  in  the  adoption  of 
better  methods  and  equipment  for  ('add  sampling,  and  for  laboratory 
procedure.  An  important  feature  of  the  cooperative  investigation  has 
been  to  collect  new  samples  and  to  review  the  entire  subject  of  the 
quality  of  Illinois  coals.      (See  p.  26.) 

The  general  characteristics  of  Illinois  coal  have  been  presented1  as 
follows : 

"All  Illinois  coals  are  bituminous,  and,  as  contrasted  with  their  prin- 
cipal market-competitor's,  are  relatively  high  in  sulphur,  ash,  moisture, 
and  volatile  matter.  Moreover,  as  Professor  Parr  has  pointed  out,  40 
per  cent  of  the  volatile  matter,  or  14  per  cent  of  the  whole  coal,  is  non- 
combustible,  as  contrasted  with  22  and  4.2  per  cent  respectively,  in  the 
case  of  Pocahontas,  W.  Va.,  coal,  and  47  and  21.63  per  cent  in  North 
Dakota  lignite.  Illinois  coals  are  essentially  free-burning  and  non- 
coking.  They  are  mainly  used  for  heating  and  power-generation,  and 
have  no  large  or  direct  use  in  metallurgy.  The  amount  of  sulphur 
present  precludes  their  use  for  furnace-coke  and  complicates  the  problem 
of  storage.  The  large  proportion  of  volatile  matter  introduces  a  smoke- 
problem  when  the  coals  are  burned  in  cities,  and  the  high  content  of 
ash  also  detracts  from  their  value.  Despite  all  these  facts,  they  have  a 
high  average  value  for  miscellaneous  heating  and  for  steam-generation, 
and  many  of  them  are  excellently  adapted  for  use  in  gas-producers.  In 
a  general  way,  it  may  be  said  that  the   Illinois-Indiana  coals  are  not 

1  Bain,  H.  F.,  Studies  of  Illinois  Coal,  Bull.  Illinois  State  Geol.  Survey.  No.  14,  p.  187,  1909 


CHEMICAL    CHARACTER    OF    COALS. 


Of 


inherently  as  valuable  as  the  coals  of  the  Appalachian  basin,  but  more 
valuable  than  those  of  the  Michigan  and  Western  Interior  fields,  except- 
ing limited  areas  in  western  Arkansas  and  eastern  Oklahoma." 

The  analyses  from  mine  samples  published  in  Bulletin  16  indicate 
the  general  character  of  the  various  coals  in  the  important  mining- 
regions  of  the  State.  The  following  statement  presents  the  average 
results  from  the  old  report. 


Table  5 — Analyses  of  mine  samples   (not   exactly   indicative  of  com- 
mercial output) 


Coal 
bed. 


Counties. 


No. 
of  anal- 
yses. 


Coal  as  received. 


Moisture. 


Ash. 


Sulphur. 


B.  t.  u. 


Fulton 

Mercer 

Rock  Island. 


f  Bureau . . . 

|  LaSalle... 

j  Marshall. . 

Putnam. . 

I  [Woodford. 

/  Grundy . . . 
\Will 


Jackson . 


Fulton.. 
Peoria. . . 
Tazewell 


f  Logan 

J  Macon 

j  Menard  . . . 
(  Sangamon. 


/Gallatin. 
(  Saline. . 


Christian 

Clinton 

Jackson 

Jefferson 

Macon 

Macoupin 

Madison. . . . 

Marion 

Montgomery. 

Moultrie 

Perry 

Randolph. . . 

St.  Clair 

Sangamon. . . 

Shelby 

Washington . 


f  Franklin. . . 

White 

Williamson 


Vermilion. 
Vermilion. 


16.60 

14.22 

16.12 

II).  ss 

15.15 


8.95 

12.42 
13.19 


7  .52 

8.23 

."i .  1 5 

11.33 


10.65 


8.27 
9.19 


4.97 
2. si 

2.83 
1.14 

3.26 


3.16 


1 .85 

1.24 
2.90 


10,  709 

11,388 

10,850 
L2,385 

10,547 

10,658 
12,513 


11,012 


1 1 , 929 

11,110 

11,2:56 


58  COAL    MINING   INVESTIGATIONS. 

It  should  be  remembered  that  the  above  values  are  derived  from 
face  samples,  containing  all  natural  moisture,  ash,  and  sulphur,  except 
that  impurities  measuring  three-eighths  of  an  inch  or  more  in  thickness 
were  arbitrarily  excluded.  The  results  indicate  the  quality  that  can 
be  obtained  if  impurities  are  removed  from  the  coal  in  mining,  and  if 
dirt  from  roof  and  floor  are  excluded  in  loading  the  mine  cars.  Eun- 
of-mine  coal  as  shipped  usually  contains  impurities  which  were  not 
present  in  the  sample  as  analyzed.  Prepared  sizes,  especially  lump,  may 
be  slightly  superior  to  the  mine  sample.  Carefulness  or  carelessness  in 
cleaning  and  otherwise  preparing  the  mined  coal  for  shipment  may 
counteract  the  natural  qualities  inherent  in  the  coal  as  indicated  by 
the  above  table. 


59 


APPENDIX  B. 


ILLINOIS  MINING  SYSTEMS. 


INTRODUCTION 

For  the  information  of  readers  who  may  not  be   familiar  with  the 
mining  practice  in  Illinois,  a  general  description  is  here  given  of  the 
three  systems  of  mining  as  nsed  in  the  State,  namely : 
Room-and-pillar 
Unmodified 
Panel  system 
Longwall 
Stripping. 

The  choice  of  a  system  for  any  particular  mine  should  depend  upon: 
Character,  thickness,  and  weight  of  overburden 
Nature  of  roof  and  floor 
Inclination  and  thickness  of  the  seam 
Physical  character  of  the  coal 
Presence  and  pressure  of  gas  in  the  seam 
Danger  of  spontaneous  combustion,  etc. 

In  Illinois  the  coal  in  practically  all  of  the  shipping  mines  is  reached 
by  shafts,  and  the  drift  and  slope  mines  are  nearly  all  found  among 
the  country  banks.  The  local  ion  of  the  -hall,  slope,  or  drift  depends 
on:  The  shape  of  the  property;  the  accessibility  of  a  railroad;  lie' 
direction  in  which  practice  in  I  lie  district  has  proven  that  entry  and 
room  driving  causes  fewesl  roof  fall-  and  produces  the  Largesi  amount 
of  lump  coal;  surface  topography;  Inclination  of  bed. 

The  surface  topography  of  the  Stale  Is  as  a  rule  a  rolling  prairie,  and 
with  few  exceptions  the  coal  beds  are  practically  Level  so  that  the 
location  of  the  mine  opening  is  determined  mainly  by  the  shape  of  the 
property  and  the  shipping  facilities. 

When  the  coal  has  been  reached  and  the  hot  loin  arranged,  if  neces- 
sary, the  procedure  varies  according  to  the  system  of  mining  adopted. 

KOOM-AND-PILLAB    SYSTEM 

UNMODIFIED   ROOM-AND-PILLAR   SYSTEM 

As  shown  in  fig.  17  (p.  GO)  in  a  typical  room-and-pillar  shaft-mine 
two  parallel  entries,  one  used  for  haulage  ("A")  called  the  main  entry 
and  one  for  carrying  the   ventilating  current    ("B")    called    the   back 


60 


COAL    MINING    INVESTIGATIONS. 


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MINING    SYSTEMS.  61 

entry,  are  driven  on  each  side  of  the  shaft  through  the  solid  coal  towards 
the  property  boundaries.  The  consideration  of  cleavage  or  "cleat"  in 
the  coal  does  not  generally  determine  the  direction  chosen  for  driving 
entries  or  rooms  in  Illinois.  The  main-entry-pillar  between  these  two 
entries  varies  in  width  from  1(5  to  65  feet.  The  entries  are  advanced 
simultaneously,  and  outside  the  shaft  pillar  are  connected  at  60-foot 
intervals  by  cross-cuts  for  the  purpose  of  maintaining  a  flow  of  air 
through  the  entries  to  the  "face." 

At  a  distance  from  the  shaft,  commonly  300  feet,  such  that  the  solid 
coal  surrounding  the  shaft  will  be  sufficient  to  protect  the  shaft  from 
injury  by  surface  subsidence^  a  pair  of  cross-entries  is  driven  to  the 
right  and  left  of  the  main  entries  and  at  a  right  angle  to  them.  The 
cross-entries  vary  in  width  from  8  to  20  feet,  and  the  coal  between  them, 
called  the  cross-entry-pillar,  from  12  to  50  feet. 

Rooms  are  turned  off  at  a  right  angle  to  the  cross-entries  at  a  distance 
of  •")()  to  150  feet  from  the  main  entries,  and  thereafter  at  regular 
distances. 

The  ((Til  between  the  main-entry  or  the  back-entry  and  the  first  room 
is  the  main-barrier-pillar. 

The  rooms  vary  in  width  from  L8  to  jo  feet,  hut  in  order  to  protect 
the  cross-entries  from  a  squeeze  a  room  i-  not  driven  full  width  at  first, 
hut  for  a  distance  varying  from  !»  to  is  feet  is  driven  as  a  narrow  neck 
from  ;)  to  is  feel  wide.  In  widening  the  rooms  either  of  the  two 
following   methods    is   adopted : 

1.  One  side  of  the  nook-  is  continued  in  a  straight  line  forming  a 
side  of  the  room.  In  this  case  the  width  of  the  room  is  gained  by 
driving  off  the  opposite  side  of  the  neck  at  an  angle  either  of  L5  degrees 
or  of  !)<)  degrees  from  the  direction  in  which  the  neck  was  driven,  until 
the  full   width  of  the  room  ha-  been   reached  • 

2.  An  angle  of  T>  degree.-  or  of  90  degrees  is  turned  off  each  side  of 
the  ixck.  and  when  the  full  room  width  is  reached  the  driving  is  con- 
tinued  parallel   to  the  direction  of  the   room    neck. 

The  length  of  rooms  in  Minois  varies  from  250  to  300  feet.  The 
coal  remaining  between  room-,  called  the  room-pillar,  is  from  6  to  30 
feel    in   width. 

PANEL    ROOM-AND-PILL  \i;   81  STEM 

A  mine  operated  on  the  panel  system,  ha-  room-entries  or  butt-i  ntries 
as  shown  in  fig.  is  (p.  62)  turned  oil'  in  pairs  at  intervals  of  500  to 
600  loot  along  the  cross-entries.  The  -olid  pillar  of  coal  between  tie1 
cross  entry  and  the  lir-i  room,  called  the  cross-barrier-pillar,  is  from  50 
io  125  loot  wide.  The  main-barrier-pillar  in  this  system  i-  the  pillar 
left  between  the  main-entry  and  the  ends  of  the  rooms  turned  oil'  those 
room-entries  which  are  nearest  to  the  main-entry. 

'Idie  obvious  advantage  of  the  panel  system  is  thai  each  panel  is  sur- 
rounded (in  all  sides  by  a  pillar  of  solid  coal  and  is  a  separate  unit  in 
operation.     A  squeeze  occurring  in  any  panel  is  confined  l>\  the  barrier- 


G2 


COAL    MINING    INVESTIGATIONS. 


Fig    18     Plan  of  panel  mine 


MINING    SYSTEMS.  63 

pillars,  if  large  enough.  The  ventilating  current  can  be  regulated  so  as 
to  supply  air  according  to  the  needs  of  each  panel,  and  pillar-drawing 
can  be  more  advantageously  practiced,  thus  giving  a  higher  coal-recovery. 
Whatever  modification  may  be  in  use,  room-and-pillar  mining  con- 
templates only  a  partial  extraction  of  the  coal  during  the  first  or  advance 
working.  The  pillar  coal  left  to  support  the  roof  is  gained  in  the  second 
or  retreating  working  after  the  rooms  have  been  driven  to  their  full 
length.  This  second  working  is  known  as  drawing  or  robbing  the  pillars 
and  has  been  little  practiced  in  Illinois  up  to  the  present  time,  partly 
through  fear  of  surface  subsidence  and  subsequent  damage  suits,  and 
partly  in  the  older  mines  because  of  unsystematic  working  and  too  small 
pillars.  Many  of  the  newer  mines  have  been  systematically  projected 
and  are  being  worked  to  secure  the  pillar  coal. 

LONGWALL  SYSTEM 

According  to  the  longwall  system  as  shown  by  an  actual  mine  map 
in  fig.  19  (p.  64)  the  entire  bed  is  removed  as  the  work  progresses,  the 
roof  at  the  face  being  supported  by  timber,  gob,  and  pack-walls,  and 
the  necessary  roadways  being  maintained  by  pack-walls.  A  pillar  of 
coal  is  usually  left  surrounding  the  .-haft  for  its  protection  from  the 
subsidence  of  the  surrounding  strata.  On  each  side  of  the  shafl  a  main 
haulage  way  is  driven;  from  the  air  shaft  a  similar  entry  is  driven  al  a 
right  angle  to  the  first.  In  some  cases  these  haulage  ways  are  paralleled 
by  other  passages  used  as  air  courses.  When  the  single  entries  or  the 
two  pairs  of  entries,  as  the  case  may  hi',  have  been  driven  a  distance  suffi- 
cient to  provide  the  desired  shafl  pillar  an  entry  is  driven  i<»  righl  and 
left  of  each  pair  of  cut  ries  or  of  each  single  entry.  These  entries-around- 
pillar  block  out  the  shaft  pillar  and  establish  the  longwall  face. 

After  the  shall  pillar  has  been  blocked  out  the  main  haulage  entry  'is 
continued,  and  at  an  angle  usually  of  L5  degrees  to  it  cross-entries  are 
turned  oil'  on  each  side  at   intervals  of  200  to    :'><>(>    feet.       From    these 

cross-entries  r< is  are  driven  at  an  angle  of   to  degrees.     Room-centers 

are  usually  <i<»  feel  as  measured  along  the  cross  entries,  or  [2  feet  ;ii 
the  working  Face.  The  work,  once  begun,  progresses  in  a  long  continu- 
ous face.  Pari  of  the  waste  secured  in  mining  and  in  brushing  the  roof 
to  maintain  heighl  of  roadways  is  used  to  lill  the  -pace  left  by  the 
removal  of  the  coal.  The  remainder  of  the  waste  is  hoisted  out.  In 
northern   Illinois  there  is  hoisted  aboul  one-third  as  much   rock  as  coal. 

The  longwall  system  is  most  applicable  in  Illinois  to  thin  coal  seams 
which  have  a  flexible  or  'tender"  roof  and  a  soft  fire-clay  floor.  In  order 
to  prevent  squeezes,  that  is.  closing  of  entries  of  places,  the  dirl  obtained 
from  mining  the  floor  under  the  coal  together  with  the  rock  obtained 
from  brushing  the  roof  to  give  sufficienl  height  of  entry  for  mule  haul- 
age should  completely  (ill  the-  space  between  roof  and  floor  after  the  coal 
i-  mined.  II'  this  space  is  not  completely  filled  or  if  the  building  of 
the  pack  walls  is  not  well  done  a  squeeze  is  liable  to  occur.  When  this 
space  is  kept  well  filled  the  weight  of  the  roof  is  thrown  on  the  coal  and 
the  coal  breaks  well.  There  are  fewer  gob-fires  in  a  well-filled  gob  than 
iu  one  only  partly  filled.  In  Illinois  the  longwall  system  is  most  ap- 
plicable to  horizontal   -cams   under   lour  and   one-half   feet    thick   because 


64  COAL    MINING    INVESTIGATIONS. 

with  thicker  coal  it  is  not  necessary  to  brush  the  roof  and  not  enough 
waste  is  secured  to  furnish  the  required  gob.  Under  ideal  conditions  the 
fire-clay   under  the  coal   should  not  exceed   one  foot  in  thickness   and 


Fig.  19.    Plan  of  longwall  mine 

should  be  underlain  by  a  hard  bottom  in  order  that  the  roof  weight  may 
break  down  the  coal  with  as  little  wedging  as  possible. 

STKIPPIXG  SYSTEM 

The  stripping  system  may  be  used  where  the  overburden  can  be  re- 
moved economically  from  the  coal  by  a  steam  shovel  or  other  mechanical 
means,  thus  exposing  the  coal,  which  is  then  practically  quarried.  There 
are  two  common  methods  of  operating  a  stripping : 


MINING    SYSTEMS. 


65 


(1)  A  "thorough-cut"  about  50  feet  wide,  as  shown  in  fig.  20 
is  made  by  the  shovel  at  the  property  line  and  the  coal  is  exposed.  A 
haulage  cut,  as  shown  in  fig.  21  connects  the  thorough-cut  with  the 
tipple  and  is  maintained  during  the  progress  of  the  stripping. 


FIG.  20.    Stripping  mine  thorough-cut 

After  the  coal  in  the  thorough-cut  is  exposed,  the  seam  behind  the 
shovel  is  mined  as  shown  in  fig.  22.  On  reaching  the  end  of  the  thorough- 
cut  the  shovel,  as  shown  in  fig.  23,  makes  a  cut  paralleling  the  thorough- 


Fio.  21.    Stripping  miae  haulage  way 


— 5  M  I 


66 


COAL   MINING   INVESTIGATIONS. 


cut  exposing  another  strip  of  coal  about  50  feet  wide  and  depositing  the 
overburden  in  the  pit  left  by  mining  the  coal.  This  procedure  is  con- 
tinued until  the  acreage  is  mined. 


Fig.  22.    Stripping  mine  coal  face 


(2)  The  thorough-cut,  instead  of  extending  along  only  one  side  of 
the  property,  encircles  the  acreage  to  be  stripped.  The  mining  goes  on 
continually  behind  the  shovel,  and,  as  in  the  first  method,  the  dirt  is 
deposited  in  the  pit  made  by  mining  the  coal. 


"     *'•'.-.  v  ■"*■-.  '.      Ml,  .'•'•- 


Fig.  23.    Stripping  mine  gecond  cut 


67 


APPENDIX  C. 


EQUIPMENT  AND  OPERATION  OF  COAL  DUST  LABOR- 
ATORY. 


DESCRIPTION  OF  APPARATUS 

For  the  benefit  of  readers  who  may  be  interested  in  the  details  of  the 
equipment  and  methods  of  determining  the  relative  explosibility  of  the 
Illinois  coal  dusts,  the  following  description  of  the  laboratory  fitted  up 
at  Urbana  by  the  Geological  Survey  and  the  University  has  been  pre- 
pared by  the  chemist  in  charge,  Mr.  Louis  A.  Scholl,  Junior  Chemist, 
U.  S.  Bureau  of  Mines. 


Fig.  24.    Coal-dust  laboratory,  University  of  Illinois 


68 


COAL   MINING   INVESTIGATIONS. 


The  equipment  of  the  laboratory  (fig.  24)  consists  of  a  motor  gener- 
ator set  with  D.  C.  voltage  regulator,  two  laboratory  tables,  a  Becker 
analytical  balance,  two  sets  of  the  apparatus  devised  by  Dr.  J.  C.  Frazer 
for  the  testing  of  the  inflammability  of  coal-dusts  on  a  laboratory  scale, 
and  all  the  necessary  supplies  and  appurtenances  required  in  connection 
with  the  work. 

The  motor  generator  set  consists  of  a  l1/^  K.  W.  induction  motor  im- 
pelled by  a  voltage  of  440  volts,  two  phase,  60  cycles,  at  a  speed  of  1800 
E.  P.  M.  The  induction  motor  is  direct  connected  to  a  compound  wound 
D.  C.  generator  with  a  capacity  of  11.2  amperes  at  110  volts.  In  order 
to  prevent  the  voltage  of  the  D.  C.  generator  from  fluctuating  due  to  a 
dropping  in  the  speed  of  the  induction  motor  from  line  drop,  a  voltage 
regulator  was  installed.  This  operates  automatically  and  keeps  the  volt- 
age practically  constant  at  110  volts  by  cutting  in  and  out  resistance  in 
the  shunt  field  of  the  D.  C.  generator  when  the  voltage  tends  to  change. 
This  arrangement  gives  a  fairly  good  method  of  voltage  control  which 
is  essential  in  this  work. 


Fig.  25.    Explosibility  apparatus  in  coal-dust  laboratory 


The  coal  dust  ignition  apparatus  which  is  being  used  in  the  present 
investigation  is  shown  by  photograph  and  diagram  (figs.  25  and  26). 

The  apparatus  consists  of:  the  explosion  flask;  the  apparatus  for  the 
injection  of  the  dust;  the  means  of  ignition;  and  the  device  for  meas- 
uring the  pressure  developed  in  the  explosion  flask. 

The  explosion  flask  "A"  is  made  of  heavy  glass  having  a  low  coefficient 
of  expansion  in  order  to  withstand  heat.    It  has  a  capacity  of  1500  c.c. 


COAL    DUST    LABORATORY. 


69 


This  flask  has  large  tubulures  at  each  end  which  are  ground  true.  The 
lower  tubulure  which  is  the  smaller,  is  surrounded  by  a  rubber  band  "B" 
projecting  over  the  ground  end.  This  acts  as  a  gasket,  affording  a  gas 
tight  connection  when  placed  upon  the  brass  plate  containing  the  appar- 
atus for  the  injection  of  the  dust. 


Fig.  26.     Detail  of  dual  explcsibility  apparal 


The  injection  apparatus  consists  of  a  small  glass  funnel  "C"  cemented 
into  the  brass  plate  "D."  A  piece  of  30-mesh  copper  gauze  covers  the 
top  of  the  funnel  and  serves  In  disseminate  the  <lus(  into  ;i  cloud  when 
the  dust  is  ejected  from  the  funnel  int!>  the  flask  by  the  release  of  the 
compressed  air  contained  in  the  pressure  bulb  "K."  Before  ejecting 
(he  dust  into  the  flask,  air  is  compressed  in  bulb  "E"  by  means  of  the 
compression  bulb  "F"  until  a  pressure  of  200  in. in.  of  mercury  is  in- 
dicated by  the  manometer  "G." 


70  COAL   MINING   INVESTIGATIONS. 

The  source  of  ignition  is  a  coil  of  100  cm.  of  No.  26  B  &  S  gage  plat- 
inum wire  "H"  wound  upon  quartz  insulators  which  are  attached  to  the 
heavy  nickel  leads  "I."  The  temperature  of  this  coil  can  at  all  times 
be  accurately  determined  by  finding  the  resistance  of  the  platinum  wire 
for  any  given  current  strength.  The  nickel  leads  pass  through  wooden 
bushings  in  the  top  brass  plate  and  serve  to  suspend  the  coil  in  the 
center  of  the  explosion  flask.  The  ends  of  the  platinum  wire  are 
soldered  with  silver  to  the  nickel  leads.  The  underside  of  the  brass  plate 
is  covered  with  a  piece  of  gasket  rubber.  The  coil  is  heated  by  passing 
through  it  a  direct  current  of  110  volts. 

The  device  used  to  measure  the  pressure  developed  in  the  flask  is 
made  up  of  a  small  50  c.c.  flask  "K"  containing  a  weighed  amount  of 
mercury,  and  a  small  steel  ball  "L"  which  is  ground  with  emery  powder 
to  fit  practically  gas-tight  into  the  brass  tube  "M."  This  tube  has  an 
internal  diameter  of  7  mm.  and  communicates  with  the  interior  of  the 
large  flask.  "N"  is  a  glass  tube  which  slips  into  the  neck  of  the  flask 
containing  the  mercury  and  serves  to  keep  it  in  position  on  the  steel 
ball. 

OPERATION  OF  APPARATUS 

A  weighed  amount  of  dust  (0.05  grams)  is  placed  in  a  uniform  posi- 
tion in  the  funnel.  The  funnel  is  next  connected  to  the  pressure  bulb 
"E"  by  means  of  a  short  piece  of  rubber  tubing  closed  with  a  pinch-cock 
"O"  and  placed  in  a  shaped  receptacle  in  the  wooden  block  "P."  Using 
the  compression  bulb  "J?"  the  air  in  "E"  is  compressed  to  a  pressure  of 
200  mm.  of  mercury,  as  indicated  by  the  manometer  "G."  The  explosion 
flask  is  then  placed  in  position  upon  the  brass  plate  "D."  The  upper 
brass  plate,  to  which  the  coil  is  attached,  is  placed  in  position  with  the 
coil  in  the  center  of  the  flask.  Gas  tight  connection  between  the  upper 
brass  plate  and  the  ground  edge  of  the  top  tubulure  is  made  by  means 
of  the  rubber  gasket  glued  to  the  bottom  of  the  brass  plate.  In  order 
to  obtain  good  contacts  between  the  brass  plates  and  the  tubulures  a 
steel  plate  is  fitted  over  the  top  brass  plate  and  tightened  by  turning 
the  nuts  on  the  two  draw  bolts.  The  steel  ball  is  greased  with  vaseline 
and  placed  in  position  upon  the  brass  tube  "M"  with  the  flask  "K"  rest- 
ing upon  the  top  of  the  ball.  Electrical  connection  is  made  with 
leads  "QQ." 

After  the  apparatus  has  been  thus  assembled,  the  desired  current  is 
passed  through  the  platinum  coil  for  exactly  three  minutes,  the  expand- 
ing air  in  the  flask  being  released  by  lifting  the  steel  ball  at  intervals 
of  1,  2,  and  2%  minutes.  At  the  expiration  of  the  third  minute  the 
dust  in  the  funnel  is  blown  into  the  flask  by  the  air  pressure  when  the 
pinch-cock  is  opened.  To  prevent  back-pressure  in  the  pressure  bulb,  a 
check  valve  "R"  is  plated  in  the  rubber  tubing  between  the  pinch-cock 
and  the  funnel. 

The  pressure  developed  by  the  combustion  of  a  definite  amount  of  dust 
at  a  particular  temperature  is  determined  by  ascertaining  by  repeated 
trials  the  smallest  weight  of  mercury  which  must  be  placed  in  the 
flask  to  prevent  the  steel  ball  from  being  lifted  from  its  position.     The 


COAL    DUST    LABORATORY.  71 

lifting  of  the  ball  and  flask  of  mercury  by  the  explosion  or  igniting  of 
the  dust  is  made  evident  by  the  disturbance  of  mercury  in  the  flask,  by 
the  noise  of  the  escaping  gas,  and  bv  the  presence  of  carbon  on  the  steel 
ball. 

The  experiments  at  a  particular  temperature  are  repeated,  the  weight 
of  mercury  being  altered  each  time,  until  the  pressure  is  found  to  lie  be- 
tween two  weights  five  grams  apart.  The  mean  of  the  two  values  is  then 
accepted  as  the  maximum  pressure  which  each  dust  being  studied  is  able 
to  produce  at  the  temperature  used.  The  maximum  pressure  which  each 
dust  will  develop  is  determined  in  the  above  manner  for  five  tempera- 
tures corresponding  to  five  current  strengths,  viz :  5.0-5.5-6.0-0.5-6.0 
amperes.  By  plotting  the  five  pressures  against  the  corresponding  tem- 
peratures a  clear  conception  of  the  behavior  of  the  different  dusts  can  be 
readily  gained  and  also  a  means  of  comparing  the  different  coals  (see  fig. 
14).  In  all  experiments  0.05  grams  of  the  dust  arc  used,  and  the  result- 
ant pressure  checks  consistently  if  identical  conditions  are  maintained 
for  all  experiments.  It  is  essential  to  have  a  steady  current,  and  for  this 
purpose  an  ammeter  is  always  in  circuit,  the  current  being  regulated  very 
closely  by  means  of  a  rheostat. 


\ 


